juplo.de Git - demos/kafka/wordcount/blob - src/main/java/de/juplo/kafka/wordcount/top10/Top10StreamProcessor.java

   1 package de.juplo.kafka.wordcount.top10;
   2
   3 import com.fasterxml.jackson.core.JsonProcessingException;
   4 import com.fasterxml.jackson.databind.ObjectMapper;
   5 import lombok.extern.slf4j.Slf4j;
   6 import org.apache.kafka.clients.consumer.ConsumerConfig;
   7 import org.apache.kafka.common.serialization.Serdes;
   8 import org.apache.kafka.streams.KafkaStreams;
   9 import org.apache.kafka.streams.KeyValue;
  10 import org.apache.kafka.streams.StreamsBuilder;
  11 import org.apache.kafka.streams.StreamsConfig;
  12 import org.springframework.boot.SpringApplication;
  13 import org.springframework.context.ConfigurableApplicationContext;
  14 import org.springframework.stereotype.Component;
  15
  16 import javax.annotation.PostConstruct;
  17 import javax.annotation.PreDestroy;
  18 import java.util.Properties;
  19 import java.util.concurrent.CompletableFuture;
  20 import java.util.regex.Pattern;
  21
  22 import static org.apache.kafka.streams.errors.StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse.SHUTDOWN_CLIENT;
  23
  24
  25 @Slf4j
  26 @Component
  27 public class Top10StreamProcessor
  28 {
  29         final static Pattern PATTERN = Pattern.compile("\\W+");
  30
  31         public final KafkaStreams streams;
  32
  33
  34         public Top10StreamProcessor(
  35                         Top10ApplicationProperties properties,
  36                         ObjectMapper mapper,
  37                         ConfigurableApplicationContext context)
  38         {
  39                 StreamsBuilder builder = new StreamsBuilder();
  40
  41                 builder
  42                                 .<String, String>stream(properties.getInputTopic())
  43                                 .map((keyJson, countStr) ->
  44                                 {
  45                                         try
  46                                         {
  47                                                 Key key = mapper.readValue(keyJson, Key.class);
  48                                                 Long count = Long.parseLong(countStr);
  49                                                 Entry entry = Entry.of(key.getWord(), count);
  50                                                 String entryJson = mapper.writeValueAsString(entry);
  51                                                 return new KeyValue<>(key.getUsername(), entryJson);
  52                                         }
  53                                         catch (JsonProcessingException e)
  54                                         {
  55                                                 throw new RuntimeException(e);
  56                                         }
  57                                 })
  58                                 .groupByKey()
  59                                 .aggregate(
  60                                                 () -> "{\"entries\"     : []}",
  61                                                 (username, entryJson, rankingJson) ->
  62                                                 {
  63                                                         try
  64                                                         {
  65                                                                 Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
  66                                                                 ranking.add(mapper.readValue(entryJson, Entry.class));
  67                                                                 return mapper.writeValueAsString(ranking);
  68                                                         }
  69                                                         catch (JsonProcessingException e)
  70                                                         {
  71                                                                 throw new RuntimeException(e);
  72                                                         }
  73                                                 }
  74                                 )
  75                                 .toStream()
  76                                 .to(properties.getOutputTopic());
  77
  78                 Properties props = new Properties();
  79                 props.put(StreamsConfig.APPLICATION_ID_CONFIG, properties.getApplicationId());
  80                 props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, properties.getBootstrapServer());
  81                 props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
  82                 props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
  83                 props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
  84
  85                 streams = new KafkaStreams(builder.build(), props);
  86                 streams.setUncaughtExceptionHandler((Throwable e) ->
  87                 {
  88                         log.error("Unexpected error!", e);
  89                         CompletableFuture.runAsync(() ->
  90                         {
  91                                 log.info("Stopping application...");
  92                                 SpringApplication.exit(context, () -> 1);
  93                         });
  94                         return SHUTDOWN_CLIENT;
  95                 });
  96         }
  97
  98         @PostConstruct
  99         public void start()
 100         {
 101                 log.info("Starting Stream-Processor");
 102                 streams.start();
 103         }
 104
 105         @PreDestroy
 106         public void stop()
 107         {
 108                 log.info("Stopping Stream-Processor");
 109                 streams.close();
 110         }
 111 }