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.kafka.trogdor.workload;
  
  import com.fasterxml.jackson.annotation.JsonCreator;
  import com.fasterxml.jackson.annotation.JsonProperty;
  
  import java.util.ArrayList;
  import java.util.List;
  import java.util.Random;
  
  
  /**
   * A PayloadGenerator which generates pseudo-random payloads based on other PayloadGenerators.
   *
   * Given a seed and non-null list of RandomComponents, RandomComponentPayloadGenerator
   * will use any given generator in its list of components a percentage of the time based on the 
   * percent field in the RandomComponent. These percent fields must be integers greater than 0 
   * and together add up to 100. The payloads generated can be reproduced from run to run.
   * 
   * An example of how to include this generator in a Trogdor taskSpec is shown below.
   * #{@code
   *    "keyGenerator": {
   *        "type": "randomComponent",
   *        "seed": 456,
   *        "components": [
   *          {
   *            "percent": 50,
   *            "component": {
   *              "type": "null"
   *            }
   *          },
   *          {
   *            "percent": 50,
   *            "component": {
   *              "type": "uniformRandom",
   *              "size": 4,
   *              "seed": 123,
   *              "padding": 0
   *            }
   *          }
   *        ]
   *    }
   * }
   */
  public class RandomComponentPayloadGenerator implements PayloadGenerator {
      private final long seed;
      private final List<RandomComponent> components;
      private final Random random = new Random();
  
      @JsonCreator
      public RandomComponentPayloadGenerator(@JsonProperty("seed") long seed,
                                             @JsonProperty("components") List<RandomComponent> components) {
          this.seed = seed;
          if (components == null || components.isEmpty()) {
              throw new IllegalArgumentException("Components must be a specified, non-empty list of RandomComponents.");
          }
          int sum = 0;
          for (RandomComponent component : components) {
              if (component.percent() < 1) {
                  throw new IllegalArgumentException("Percent value must be greater than zero.");
              }
              sum += component.percent();
          }
          if (sum != 100) {
              throw new IllegalArgumentException("Components must be a list of RandomComponents such that the percent fields sum to 100");
          }
          this.components = new ArrayList<>(components);
      }
  
      @JsonProperty
      public long seed() {
          return seed;
      }
  
      @JsonProperty
      public List<RandomComponent> components() {
          return components;
      }
  
      @Override
      public byte[] generate(long position) {
          int randPercent;
          synchronized (random) {
              random.setSeed(seed + position);
              randPercent = random.nextInt(100);
          }
          int curPercent = 0;
          RandomComponent com = components.get(0);
          for (RandomComponent component : components) {
              curPercent += component.percent();
              if (curPercent > randPercent) {
                  com = component;
                  break;
              }
          }
          return com.component().generate(position);
      }
  }
  