heron/api/src/scala/org/apache/heron/streamlet/scala/SerializableTransformer.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.streamlet.scala

import java.io.Serializable

import org.apache.heron.streamlet.Context

/**
  * All user supplied transformation functions have to be serializable.
  * Thus all Streamlet transformation definitions take Serializable
  * Functions as their input. We simply decorate java.util. function
  * definitions with a Serializable tag to ensure that any supplied
  * lambda functions automatically become serializable.
  */
trait SerializableTransformer[I, O] extends Serializable {
  def setup(context: Context): Unit

  def transform(i: I, f: O => Unit): Unit

  def cleanup(): Unit
}