statefun-flink/statefun-flink-core/src/main/java/org/apache/flink/statefun/flink/core/translation/RouterTranslator.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 org.apache.flink.statefun.flink.core.translation;

import java.util.Map;
import org.apache.flink.api.common.typeinfo.TypeInformation;
import org.apache.flink.statefun.flink.core.StatefulFunctionsConfig;
import org.apache.flink.statefun.flink.core.StatefulFunctionsJobConstants;
import org.apache.flink.statefun.flink.core.StatefulFunctionsUniverse;
import org.apache.flink.statefun.flink.core.common.Maps;
import org.apache.flink.statefun.flink.core.message.Message;
import org.apache.flink.statefun.sdk.io.IngressIdentifier;
import org.apache.flink.statefun.sdk.io.IngressSpec;
import org.apache.flink.streaming.api.datastream.DataStream;

final class RouterTranslator {
  private final StatefulFunctionsUniverse universe;

  private final StatefulFunctionsConfig configuration;

  RouterTranslator(StatefulFunctionsUniverse universe, StatefulFunctionsConfig configuration) {
    this.universe = universe;
    this.configuration = configuration;
  }

  Map<IngressIdentifier<?>, DataStream<Message>> translate(
      Map<IngressIdentifier<?>, DataStream<?>> sources) {
    return Maps.transformValues(
        universe.routers(), (id, unused) -> createRoutersForSource(id, sources.get(id)));
  }

  /**
   * For each input {@linkplain DataStream} (created as a result of {@linkplain IngressSpec}
   * translation) we attach a single FlatMap function that would invoke all the defined routers for
   * that spec. Please note that the FlatMap function must have the same parallelism as the
   * {@linkplain DataStream} it is attached to, so that we keep per key ordering.
   */
  @SuppressWarnings("unchecked")
  private DataStream<Message> createRoutersForSource(
      IngressIdentifier<?> id, DataStream<?> sourceStream) {
    IngressIdentifier<Object> castedId = (IngressIdentifier<Object>) id;
    DataStream<Object> castedSource = (DataStream<Object>) sourceStream;

    IngressRouterOperator<Object> router = new IngressRouterOperator<>(configuration, castedId);

    TypeInformation<Message> typeInfo = universe.types().registerType(Message.class);

    int sourceParallelism = castedSource.getParallelism();

    String operatorName = StatefulFunctionsJobConstants.ROUTER_NAME + " (" + castedId.name() + ")";
    return castedSource
        .transform(operatorName, typeInfo, router)
        .setParallelism(sourceParallelism)
        .returns(typeInfo);
  }
}