com.dataartisans.flink.dataflow.translation.wrappers.SinkOutputFormat.java Source code

Introduction

Here is the source code for com.dataartisans.flink.dataflow.translation.wrappers.SinkOutputFormat.java

Source

/*
 * Copyright 2015 Data Artisans GmbH
 *
 * Licensed 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 com.dataartisans.flink.dataflow.translation.wrappers;

import com.fasterxml.jackson.databind.ObjectMapper;
import com.google.cloud.dataflow.sdk.io.Sink;
import com.google.cloud.dataflow.sdk.options.PipelineOptions;
import com.google.common.base.Preconditions;
import com.google.cloud.dataflow.sdk.transforms.Write;
import org.apache.flink.api.common.io.OutputFormat;
import org.apache.flink.configuration.Configuration;
import org.apache.flink.util.AbstractID;

import java.io.IOException;
import java.io.ObjectInputStream;
import java.io.ObjectOutputStream;
import java.lang.reflect.Field;

/**
 * Wrapper class to use generic Write.Bound transforms as sinks.
 * @param <T> The type of the incoming records.
 */
public class SinkOutputFormat<T> implements OutputFormat<T> {

    private final Sink<T> sink;

    private transient PipelineOptions pipelineOptions;

    private Sink.WriteOperation<T, ?> writeOperation;
    private Sink.Writer<T, ?> writer;

    private AbstractID uid = new AbstractID();

    public SinkOutputFormat(Write.Bound<T> transform, PipelineOptions pipelineOptions) {
        this.sink = extractSink(transform);
        this.pipelineOptions = Preconditions.checkNotNull(pipelineOptions);
    }

    private Sink<T> extractSink(Write.Bound<T> transform) {
        // TODO possibly add a getter in the upstream
        try {
            Field sinkField = transform.getClass().getDeclaredField("sink");
            sinkField.setAccessible(true);
            @SuppressWarnings("unchecked")
            Sink<T> extractedSink = (Sink<T>) sinkField.get(transform);
            return extractedSink;
        } catch (NoSuchFieldException | IllegalAccessException e) {
            throw new RuntimeException("Could not acquire custom sink field.", e);
        }
    }

    @Override
    public void configure(Configuration configuration) {
        writeOperation = sink.createWriteOperation(pipelineOptions);
        try {
            writeOperation.initialize(pipelineOptions);
        } catch (Exception e) {
            throw new RuntimeException("Failed to initialize the write operation.", e);
        }
    }

    @Override
    public void open(int taskNumber, int numTasks) throws IOException {
        try {
            writer = writeOperation.createWriter(pipelineOptions);
        } catch (Exception e) {
            throw new IOException("Couldn't create writer.", e);
        }
        try {
            writer.open(uid + "-" + String.valueOf(taskNumber));
        } catch (Exception e) {
            throw new IOException("Couldn't open writer.", e);
        }
    }

    @Override
    public void writeRecord(T record) throws IOException {
        try {
            writer.write(record);
        } catch (Exception e) {
            throw new IOException("Couldn't write record.", e);
        }
    }

    @Override
    public void close() throws IOException {
        try {
            writer.close();
        } catch (Exception e) {
            throw new IOException("Couldn't close writer.", e);
        }
    }

    private void writeObject(ObjectOutputStream out) throws IOException, ClassNotFoundException {
        out.defaultWriteObject();
        ObjectMapper mapper = new ObjectMapper();
        mapper.writeValue(out, pipelineOptions);
    }

    private void readObject(ObjectInputStream in) throws IOException, ClassNotFoundException {
        in.defaultReadObject();
        ObjectMapper mapper = new ObjectMapper();
        pipelineOptions = mapper.readValue(in, PipelineOptions.class);
    }
}