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

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Here is the source code for org.apache.beam.runners.direct.WindowEvaluatorFactory.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.Collection;
import javax.annotation.Nullable;
import org.apache.beam.sdk.runners.AppliedPTransform;
import org.apache.beam.sdk.transforms.PTransform;
import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
import org.apache.beam.sdk.transforms.windowing.Window;
import org.apache.beam.sdk.transforms.windowing.WindowFn;
import org.apache.beam.sdk.util.WindowedValue;
import org.apache.beam.sdk.values.PCollection;
import org.joda.time.Instant;

/**
 * The {@link DirectRunner} {@link TransformEvaluatorFactory} for the
 * {@link Window.Assign} primitive {@link PTransform}.
 */
class WindowEvaluatorFactory implements TransformEvaluatorFactory {
    private final EvaluationContext evaluationContext;

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

    @Override
    public <InputT> TransformEvaluator<InputT> forApplication(AppliedPTransform<?, ?, ?> application,
            @Nullable CommittedBundle<?> inputBundle) throws Exception {
        return createTransformEvaluator((AppliedPTransform) application);
    }

    private <InputT> TransformEvaluator<InputT> createTransformEvaluator(
            AppliedPTransform<PCollection<InputT>, PCollection<InputT>, Window.Assign<InputT>> transform) {
        WindowFn<? super InputT, ?> fn = transform.getTransform().getWindowFn();
        UncommittedBundle<InputT> outputBundle = evaluationContext
                .createBundle((PCollection<InputT>) Iterables.getOnlyElement(transform.getOutputs().values()));
        if (fn == null) {
            return PassthroughTransformEvaluator.create(transform, outputBundle);
        }
        return new WindowIntoEvaluator<>(transform, fn, outputBundle);
    }

    @Override
    public void cleanup() {
    }

    private static class WindowIntoEvaluator<InputT> implements TransformEvaluator<InputT> {
        private final AppliedPTransform<PCollection<InputT>, PCollection<InputT>, Window.Assign<InputT>> transform;
        private final WindowFn<InputT, ?> windowFn;
        private final UncommittedBundle<InputT> outputBundle;

        @SuppressWarnings("unchecked")
        public WindowIntoEvaluator(
                AppliedPTransform<PCollection<InputT>, PCollection<InputT>, Window.Assign<InputT>> transform,
                WindowFn<? super InputT, ?> windowFn, UncommittedBundle<InputT> outputBundle) {
            this.outputBundle = outputBundle;
            this.transform = transform;
            // Safe contravariant cast
            this.windowFn = (WindowFn<InputT, ?>) windowFn;
        }

        @Override
        public void processElement(WindowedValue<InputT> compressedElement) throws Exception {
            for (WindowedValue<InputT> element : compressedElement.explodeWindows()) {
                Collection<? extends BoundedWindow> windows = assignWindows(windowFn, element);
                outputBundle.add(WindowedValue.<InputT>of(element.getValue(), element.getTimestamp(), windows,
                        element.getPane()));
            }
        }

        private <W extends BoundedWindow> Collection<? extends BoundedWindow> assignWindows(
                WindowFn<InputT, W> windowFn, WindowedValue<InputT> element) throws Exception {
            WindowFn<InputT, W>.AssignContext assignContext = new DirectAssignContext<>(windowFn, element);
            Collection<? extends BoundedWindow> windows = windowFn.assignWindows(assignContext);
            return windows;
        }

        @Override
        public TransformResult<InputT> finishBundle() throws Exception {
            return StepTransformResult.<InputT>withoutHold(transform).addOutput(outputBundle).build();
        }
    }

    private static class DirectAssignContext<InputT, W extends BoundedWindow>
            extends WindowFn<InputT, W>.AssignContext {
        private final WindowedValue<InputT> value;

        public DirectAssignContext(WindowFn<InputT, W> fn, WindowedValue<InputT> value) {
            fn.super();
            this.value = value;
        }

        @Override
        public InputT element() {
            return value.getValue();
        }

        @Override
        public Instant timestamp() {
            return value.getTimestamp();
        }

        @Override
        public BoundedWindow window() {
            return Iterables.getOnlyElement(value.getWindows());
        }

    }
}