org.apache.beam.runners.dataflow.worker.StreamingPCollectionViewWriterParDoFn.java Source code

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Here is the source code for org.apache.beam.runners.dataflow.worker.StreamingPCollectionViewWriterParDoFn.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.dataflow.worker;

import static com.google.common.base.Preconditions.checkState;

import com.google.common.collect.Iterables;
import org.apache.beam.runners.dataflow.worker.util.common.worker.ParDoFn;
import org.apache.beam.runners.dataflow.worker.util.common.worker.Receiver;
import org.apache.beam.sdk.coders.Coder;
import org.apache.beam.sdk.coders.IterableCoder;
import org.apache.beam.sdk.transforms.windowing.BoundedWindow;
import org.apache.beam.sdk.util.WindowedValue;
import org.apache.beam.sdk.values.TupleTag;

/**
 * A {@link ParDoFn} that writes side input data using {@link
 * StreamingModeExecutionContext.StreamingModeStepContext#writePCollectionViewData}.
 */
public class StreamingPCollectionViewWriterParDoFn implements ParDoFn {

    private final StreamingModeExecutionContext.StreamingModeStepContext stepContext;
    private final TupleTag<?> viewTag;
    private final Coder<Object> elemCoder;
    private final Coder<BoundedWindow> windowCoder;

    public StreamingPCollectionViewWriterParDoFn(StreamingModeExecutionContext.StreamingModeStepContext stepContext,
            TupleTag<?> viewTag, Coder<Object> elemCoder, Coder<BoundedWindow> windowCoder) {
        this.stepContext = stepContext;
        this.viewTag = viewTag;
        this.elemCoder = elemCoder;
        this.windowCoder = windowCoder;
    }

    @Override
    public void startBundle(Receiver... receivers) throws Exception {
        checkState(receivers.length == 1, "%s.startBundle() called with %s receivers, expected exactly 1. "
                + "This is a bug in the Dataflow service", getClass().getSimpleName(), receivers.length);
    }

    @Override
    public void processElement(Object element) throws Exception {
        WindowedValue<Iterable<Object>> elemsToWrite = (WindowedValue<Iterable<Object>>) element;
        BoundedWindow window = Iterables.getOnlyElement(elemsToWrite.getWindows());

        stepContext.writePCollectionViewData(viewTag, elemsToWrite.getValue(), IterableCoder.of(elemCoder), window,
                windowCoder);
    }

    @Override
    public void processTimers() {
    }

    @Override
    public void finishBundle() throws Exception {
    }

    @Override
    public void abort() throws Exception {
        // no-op as long as it remains stateless
    }
}