integration_test/src/scala/org/apache/heron/integration_test/topology/scala_streamlet_with_filter_and_transform/ScalaStreamletWithFilterAndTransform.scala

/**
 * 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.heron.integration_test.topology.scala_streamlet_with_filter_and_transform

import java.util.concurrent.atomic.AtomicInteger

import org.apache.heron.api.Config
import org.apache.heron.integration_test.core.TestTopologyBuilder
import org.apache.heron.streamlet.Context

import org.apache.heron.integration_test.common.{
  AbstractTestTopology,
  ScalaIntegrationTestBase
}
import org.apache.heron.streamlet.scala.{
  Builder, SerializableTransformer
}

object ScalaStreamletWithFilterAndTransform {
  def main(args: Array[String]): Unit = {
    val conf = new Config
    val topology = new ScalaStreamletWithFilterAndTransform(args)
    topology.submit(conf)
  }
}

/**
  * Scala Streamlet Integration Test
  */
class ScalaStreamletWithFilterAndTransform(args: Array[String])
    extends AbstractTestTopology(args)
    with ScalaIntegrationTestBase {

  override protected def buildTopology(
      testTopologyBuilder: TestTopologyBuilder): TestTopologyBuilder = {
    val atomicInteger = new AtomicInteger

    val streamletBuilder = Builder.newBuilder

    streamletBuilder
      .newSource(() => atomicInteger.getAndIncrement())
      .setName("incremented-numbers")
      .filter((i: Int) => i <= 7)
      .setName("numbers-lower-than-8")
      .transform[String](new TextTransformer())
      .setName("numbers-transformed-to-text")

    build(testTopologyBuilder, streamletBuilder)
  }

}

private class TextTransformer extends SerializableTransformer[Int, String] {
  private val alphabet = List("a", "b", "c", "d", "e", "f", "g", "h")

  override def setup(context: Context): Unit = {}

  override def transform(i: Int, fun: String => Unit): Unit =
    fun(s"${alphabet(i)}-$i".toUpperCase)

  override def cleanup(): Unit = {}
}