InstrumentedDataWriterDecorator.java

/*
 * 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 gobblin.instrumented.writer;

import java.io.IOException;
import java.util.Map;

import com.google.common.base.Optional;
import com.google.common.base.Preconditions;

import gobblin.configuration.State;
import gobblin.instrumented.Instrumented;
import gobblin.metrics.MetricContext;
import gobblin.source.extractor.CheckpointableWatermark;
import gobblin.util.Decorator;
import gobblin.util.DecoratorUtils;
import gobblin.util.FinalState;
import gobblin.writer.AcknowledgableRecordEnvelope;
import gobblin.writer.DataWriter;
import gobblin.writer.WatermarkAwareWriter;


/**
 * Decorator that automatically instruments {@link gobblin.writer.DataWriter}. Handles already instrumented
 * {@link gobblin.instrumented.writer.InstrumentedDataWriter} appropriately to avoid double metric reporting.
 */
public class InstrumentedDataWriterDecorator<D> extends InstrumentedDataWriterBase<D> implements Decorator, WatermarkAwareWriter<D> {

  private DataWriter<D> embeddedWriter;
  private boolean isEmbeddedInstrumented;
  private Optional<WatermarkAwareWriter> watermarkAwareWriter;

  public InstrumentedDataWriterDecorator(DataWriter<D> writer, State state) {
    super(state, Optional.<Class<?>> of(DecoratorUtils.resolveUnderlyingObject(writer).getClass()));
    this.embeddedWriter = this.closer.register(writer);
    this.isEmbeddedInstrumented = Instrumented.isLineageInstrumented(writer);
    if (this.embeddedWriter instanceof WatermarkAwareWriter) {
      this.watermarkAwareWriter = Optional.of((WatermarkAwareWriter) this.embeddedWriter);
    } else {
      this.watermarkAwareWriter = Optional.absent();
    }
  }

  @Override
  public MetricContext getMetricContext() {
    return this.isEmbeddedInstrumented ? ((InstrumentedDataWriterBase<D>) this.embeddedWriter).getMetricContext()
        : super.getMetricContext();
  }

  @Override
  public void write(D record) throws IOException {
    if (this.isEmbeddedInstrumented) {
      writeImpl(record);
    } else {
      super.write(record);
    }
  }

  @Override
  public void writeImpl(D record) throws IOException {
    this.embeddedWriter.write(record);
  }

  @Override
  public void commit() throws IOException {
    this.embeddedWriter.commit();
    super.commit();
  }

  @Override
  public void cleanup() throws IOException {
    this.embeddedWriter.cleanup();
  }

  @Override
  public long recordsWritten() {
    return this.embeddedWriter.recordsWritten();
  }

  @Override
  public long bytesWritten() throws IOException {
    return this.embeddedWriter.bytesWritten();
  }

  @Override
  public State getFinalState() {
    if (this.embeddedWriter instanceof FinalState) {
      return ((FinalState) this.embeddedWriter).getFinalState();
    }
    return super.getFinalState();
  }

  @Override
  public Object getDecoratedObject() {
    return this.embeddedWriter;
  }

  @Override
  public boolean isWatermarkCapable() {
    return watermarkAwareWriter.isPresent() && watermarkAwareWriter.get().isWatermarkCapable();
  }

  @Override
  public void writeEnvelope(AcknowledgableRecordEnvelope<D> recordEnvelope)
      throws IOException {
    Preconditions.checkState(isWatermarkCapable());
    watermarkAwareWriter.get().writeEnvelope(recordEnvelope);
  }

  @Override
  public Map<String, CheckpointableWatermark> getCommittableWatermark() {
    Preconditions.checkState(isWatermarkCapable());
    return watermarkAwareWriter.get().getCommittableWatermark();
  }

  @Override
  public Map<String, CheckpointableWatermark> getUnacknowledgedWatermark() {
    Preconditions.checkState(isWatermarkCapable());
    return watermarkAwareWriter.get().getUnacknowledgedWatermark();
  }
}