juplo.de Git - demos/kafka/wordcount/blob - src/main/java/de/juplo/kafka/wordcount/query/QueryStreamProcessor.java

   1 package de.juplo.kafka.wordcount.query;
   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.*;
   9 import org.apache.kafka.streams.kstream.Materialized;
  10 import org.apache.kafka.streams.state.HostInfo;
  11 import org.apache.kafka.streams.state.QueryableStoreTypes;
  12 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  13 import org.springframework.boot.SpringApplication;
  14 import org.springframework.context.ConfigurableApplicationContext;
  15 import org.springframework.stereotype.Component;
  16
  17 import javax.annotation.PostConstruct;
  18 import javax.annotation.PreDestroy;
  19 import java.net.URI;
  20 import java.util.Optional;
  21 import java.util.Properties;
  22 import java.util.concurrent.CompletableFuture;
  23
  24 import static org.apache.kafka.streams.errors.StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse.SHUTDOWN_CLIENT;
  25
  26
  27 @Slf4j
  28 @Component
  29 public class QueryStreamProcessor
  30 {
  31         public final KafkaStreams streams;
  32         public final HostInfo hostInfo;
  33         public final String storeName = "rankingsByUsername";
  34         public final StoreQueryParameters<ReadOnlyKeyValueStore<String, String>> storeParameters;
  35         public final ObjectMapper mapper;
  36
  37
  38         public QueryStreamProcessor(
  39                         QueryApplicationProperties properties,
  40                         ObjectMapper mapper,
  41                         ConfigurableApplicationContext context)
  42         {
  43                 StreamsBuilder builder = new StreamsBuilder();
  44
  45                 builder.table(properties.getRankingInputTopic(), Materialized.as(storeName));
  46
  47                 Properties props = new Properties();
  48                 props.put(StreamsConfig.APPLICATION_ID_CONFIG, properties.getApplicationId());
  49                 props.put(StreamsConfig.APPLICATION_SERVER_CONFIG, properties.getApplicationServer());
  50                 props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, properties.getBootstrapServer());
  51                 props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
  52                 props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
  53                 props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
  54
  55                 streams = new KafkaStreams(builder.build(), props);
  56                 streams.setUncaughtExceptionHandler((Throwable e) ->
  57                 {
  58                         log.error("Unexpected error!", e);
  59                         CompletableFuture.runAsync(() ->
  60                         {
  61                                 log.info("Stopping application...");
  62                                 SpringApplication.exit(context, () -> 1);
  63                         });
  64                         return SHUTDOWN_CLIENT;
  65                 });
  66
  67                 hostInfo = HostInfo.buildFromEndpoint(properties.getApplicationServer());
  68                 storeParameters = StoreQueryParameters.fromNameAndType(storeName, QueryableStoreTypes.keyValueStore());;
  69                 this.mapper = mapper;
  70         }
  71
  72         public Optional<URI> getRedirect(String username)
  73         {
  74                 KeyQueryMetadata metadata = streams.queryMetadataForKey(storeName, username, Serdes.String().serializer());
  75                 HostInfo activeHost = metadata.activeHost();
  76                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
  77
  78                 if (activeHost.equals(this.hostInfo))
  79                 {
  80                         return Optional.empty();
  81                 }
  82
  83                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
  84                 log.debug("Redirecting to {}", location);
  85                 return Optional.of(location);
  86         }
  87
  88         public Optional<Ranking> getRanking(String username)
  89         {
  90                 return
  91                                 Optional
  92                                                 .ofNullable(streams.store(storeParameters).get(username))
  93                                                 .map(json ->
  94                                                 {
  95                                                         try
  96                                                         {
  97                                                                 return mapper.readValue(json, Ranking.class);
  98                                                         }
  99                                                         catch (JsonProcessingException e)
 100                                                         {
 101                                                                 throw new RuntimeException(e);
 102                                                         }
 103                                                 });
 104         }
 105
 106         @PostConstruct
 107         public void start()
 108         {
 109                 log.info("Starting Stream-Processor");
 110                 streams.start();
 111         }
 112
 113         @PreDestroy
 114         public void stop()
 115         {
 116                 log.info("Stopping Stream-Processor");
 117                 streams.close();
 118         }
 119 }