code: /*
   * 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 com.intel.hibench.datagen.streaming.util;
  
  import java.util.Arrays;
  import java.util.Properties;
  
  import org.apache.kafka.clients.producer.*;
  import org.apache.kafka.common.serialization.StringSerializer;
  
  /**
   * KafkaSender hold an kafka producer. It gets content from input parameter, generates records and
   * sends records to kafka.
   */
  public class KafkaSender {
  
    KafkaProducer kafkaProducer;
    CachedData cachedData;
    int recordLength;
    int intervalSpan;
  
    StringSerializer serializer = new StringSerializer();
  
    // Constructor
    public KafkaSender(String brokerList, String seedFile,
        long fileOffset, String dfsMaster, int recordLength, int intervalSpan) {
  
      // Details of KafkaProducerConfig could be find from:
      //   http://kafka.apache.org/documentation.html#producerconfigs
      Properties props = new Properties();
      props.setProperty(ProducerConfig.BOOTSTRAP_SERVERS_CONFIG, brokerList);
      props.setProperty(ProducerConfig.KEY_SERIALIZER_CLASS_CONFIG,
          "org.apache.kafka.common.serialization.ByteArraySerializer");
      props.setProperty(ProducerConfig.VALUE_SERIALIZER_CLASS_CONFIG,
          "org.apache.kafka.common.serialization.ByteArraySerializer");
      props.setProperty(ProducerConfig.ACKS_CONFIG, "1");
      props.getProperty(ProducerConfig.CLIENT_ID_CONFIG, "DataGenerator");
      this.kafkaProducer = new KafkaProducer(props);
  
      this.cachedData = CachedData.getInstance(seedFile, fileOffset, dfsMaster);
      this.recordLength = recordLength;
      this.intervalSpan = intervalSpan;
    }
  
    // The callback function will be triggered when receive ack from kafka.
    // Print error message if exception exist.
    Callback callback = new Callback() {
      public void onCompletion(RecordMetadata metadata, Exception e) {
        if (e != null)
          e.printStackTrace();
      }
    };
  
    // send content to Kafka
    public long send (String topic, long targetRecords, boolean debugMode) {
  
      long sentRecords = 0L;
      long sentBytes = 0L;
  
      while (sentRecords < targetRecords) {
        String line = cachedData.getRecord();
        String currentTime = Long.toString(System.currentTimeMillis());
  
        // Key and Value will be serialized twice.
        // 1. in producer.send method
        // 2. explicitly serialize here to count byte size.
        byte[] keyByte = serializer.serialize(topic, currentTime);
        byte[] valueByte = fillArray(keyByte, serializer.serialize(topic, line));
  
        ProducerRecord serializedRecord = new ProducerRecord(topic, keyByte, valueByte);
        kafkaProducer.send(serializedRecord, callback);
  
        //update counter
        sentRecords++;
        sentBytes = sentBytes + keyByte.length + valueByte.length;
      }
  
      return sentRecords;
    }
  
    // Get byte array with fixed length (value length + key length = recordLength)
    private byte[] fillArray(byte[] key, byte[] line) {
  
      int valueLength = recordLength - key.length;
      byte[] valueByte;
      if (valueLength > 0) {
        valueByte = new byte[valueLength];
        if (line.length < valueLength) {
          // There is no enough content in line, fill rest space with 0
          System.arraycopy(line, 0, valueByte, 0, line.length);
          Arrays.fill(valueByte, line.length, valueLength, (byte)0);
        } else {
          System.arraycopy(line, 0, valueByte, 0, valueLength);
        }
      } else {
        // recordLength is smaller than the length of key, return empty array.
        valueByte = new byte[0];
      }
      return valueByte;
    }
  
    // close kafka producer
    public void close() {
      kafkaProducer.close();
    }
  }
  