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Beam IO for Google Cloud Pub/Sub Lite

There is a newer version: 0.23.0

/*
 * Copyright 2020 Google LLC
 *
 * 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.google.cloud.pubsublite.beam;

import com.google.auto.service.AutoService;
import com.google.cloud.pubsublite.TopicPath;
import com.google.cloud.pubsublite.proto.AttributeValues;
import com.google.cloud.pubsublite.proto.PubSubMessage;
import com.google.protobuf.ByteString;
import org.apache.beam.sdk.annotations.Internal;
import org.apache.beam.sdk.schemas.io.Failure;
import org.apache.beam.sdk.schemas.io.GenericDlqProvider;
import org.apache.beam.sdk.transforms.MapElements;
import org.apache.beam.sdk.transforms.PTransform;
import org.apache.beam.sdk.values.PCollection;
import org.apache.beam.sdk.values.PDone;
import org.apache.beam.sdk.values.TypeDescriptor;

@Internal
@AutoService(GenericDlqProvider.class)
public class DlqProvider implements GenericDlqProvider {
  @Override
  public String identifier() {
    return "pubsublite";
  }

  @Override
  public PTransform, PDone> newDlqTransform(String config) {
    return new DlqTransform(TopicPath.parse(config));
  }

  private static class DlqTransform extends PTransform, PDone> {
    private final TopicPath topic;

    DlqTransform(TopicPath topic) {
      this.topic = topic;
    }

    @Override
    public PDone expand(PCollection input) {
      return input
          .apply(
              "Failure to PubSubMessage",
              MapElements.into(TypeDescriptor.of(PubSubMessage.class))
                  .via(DlqTransform::getMessage))
          .apply(
              "Write Failures to Pub/Sub Lite",
              PubsubLiteIO.write(PublisherOptions.newBuilder().setTopicPath(topic).build()));
    }

    private static PubSubMessage getMessage(Failure failure) {
      PubSubMessage.Builder builder = PubSubMessage.newBuilder();
      builder.putAttributes(
          "beam-dlq-error",
          AttributeValues.newBuilder()
              .addValues(ByteString.copyFromUtf8(failure.getError()))
              .build());
      builder.setData(ByteString.copyFrom(failure.getPayload()));
      return builder.build();
    }
  }
}