content: /*
   * 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 org.apache.beam.runners.dataflow.util.Structs.getBytes;
  import static org.apache.beam.sdk.util.Preconditions.checkArgumentNotNull;
  
  import com.google.auto.service.AutoService;
  import java.io.IOException;
  import java.io.InputStream;
  import java.util.Map;
  import org.apache.beam.runners.dataflow.util.CloudObject;
  import org.apache.beam.runners.dataflow.util.PropertyNames;
  import org.apache.beam.runners.dataflow.worker.util.common.worker.NativeReader;
  import org.apache.beam.runners.dataflow.worker.windmill.Pubsub;
  import org.apache.beam.runners.dataflow.worker.windmill.Windmill;
  import org.apache.beam.sdk.coders.Coder;
  import org.apache.beam.sdk.io.gcp.pubsub.PubsubMessage;
  import org.apache.beam.sdk.options.PipelineOptions;
  import org.apache.beam.sdk.transforms.SimpleFunction;
  import org.apache.beam.sdk.util.SerializableUtils;
  import org.apache.beam.sdk.values.WindowedValue;
  import org.apache.beam.sdk.values.WindowedValues;
  import org.apache.beam.sdk.values.WindowedValues.WindowedValueCoder;
  import org.apache.beam.vendor.guava.v32_1_2_jre.com.google.common.collect.ImmutableMap;
  import org.checkerframework.checker.nullness.qual.Nullable;
  
  /** A Reader that receives elements from Pubsub, via a Windmill server. */
  @SuppressWarnings({
    "rawtypes", // TODO(https://github.com/apache/beam/issues/20447)
    "nullness" // TODO(https://github.com/apache/beam/issues/20497)
  })
  class PubsubReader<T> extends NativeReader<WindowedValue<T>> {
    private final Coder<T> coder;
    private final StreamingModeExecutionContext context;
    // Function used to parse Windmill data.
    // If non-null, data from Windmill is expected to be a PubsubMessage protobuf.
    private final SimpleFunction<PubsubMessage, T> parseFn;
  
    PubsubReader(
        Coder<WindowedValue<T>> coder,
        StreamingModeExecutionContext context,
        SimpleFunction<PubsubMessage, T> parseFn) {
      @SuppressWarnings({"unchecked", "rawtypes"})
      WindowedValueCoder<T> windowedCoder = (WindowedValueCoder) coder;
      this.coder = windowedCoder.getValueCoder();
      this.context = context;
      this.parseFn = parseFn;
    }
  
    /** A {@link ReaderFactory.Registrar} for pubsub sources. */
    @AutoService(ReaderFactory.Registrar.class)
    public static class Registrar implements ReaderFactory.Registrar {
  
      @Override
      public Map<String, ReaderFactory> factories() {
        Factory factory = new Factory();
        return ImmutableMap.of(
            "PubsubReader", factory, "org.apache.beam.runners.dataflow.worker.PubsubSource", factory);
      }
    }
  
    static class Factory implements ReaderFactory {
      @Override
      public NativeReader<?> create(
          CloudObject cloudSourceSpec,
          Coder<?> coder,
          @Nullable PipelineOptions options,
          @Nullable DataflowExecutionContext executionContext,
          DataflowOperationContext operationContext)
          throws Exception {
        coder = checkArgumentNotNull(coder);
        @SuppressWarnings("unchecked")
        Coder<WindowedValue<Object>> typedCoder = (Coder<WindowedValue<Object>>) coder;
        SimpleFunction<PubsubMessage, Object> parseFn = null;
        byte[] attributesFnBytes =
            getBytes(cloudSourceSpec, PropertyNames.PUBSUB_SERIALIZED_ATTRIBUTES_FN, null);
        // If attributesFnBytes is set, Pubsub data will be in PubsubMessage protobuf format. The
        // array should contain a serialized Java function that accepts a PubsubMessage object. The
        // special case of a zero-length array allows pass-through of the raw protobuf.
        if (attributesFnBytes != null && attributesFnBytes.length > 0) {
          parseFn =
              (SimpleFunction<PubsubMessage, Object>)
                  SerializableUtils.deserializeFromByteArray(attributesFnBytes, "serialized fn info");
        }
        return new PubsubReader<>(
            typedCoder, (StreamingModeExecutionContext) executionContext, parseFn);
      }
    }
  
    @Override
    public NativeReaderIterator<WindowedValue<T>> iterator() throws IOException {
      return new PubsubReaderIterator(context.getWorkItem());
    }
  
    class PubsubReaderIterator extends WindmillReaderIteratorBase<T> {
      protected PubsubReaderIterator(Windmill.WorkItem work) {
        super(work);
      }
  
      @Override
      public boolean advance() throws IOException {
        if (context.workIsFailed()) {
          return false;
        }
        return super.advance();
      }
  
      @Override
      protected WindowedValue<T> decodeMessage(Windmill.Message message) throws IOException {
        T value;
        InputStream data = message.getData().newInput();
        notifyElementRead(data.available());
        if (parseFn != null) {
          Pubsub.PubsubMessage pubsubMessage = Pubsub.PubsubMessage.parseFrom(data);
          value =
              parseFn.apply(
                  new PubsubMessage(
                      pubsubMessage.getData().toByteArray(),
                      pubsubMessage.getAttributesMap(),
                      pubsubMessage.getMessageId()));
        } else {
          value = coder.decode(data, Coder.Context.OUTER);
        }
        return WindowedValues.timestampedValueInGlobalWindow(
            value, WindmillTimeUtils.windmillToHarnessTimestamp(message.getTimestamp()));
      }
    }
  
    @Override
    public boolean supportsRestart() {
      return true;
    }
  }
  