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.KStream;
  10 import org.apache.kafka.streams.kstream.KTable;
  11 import org.apache.kafka.streams.kstream.Materialized;
  12 import org.apache.kafka.streams.state.HostInfo;
  13 import org.apache.kafka.streams.state.QueryableStoreTypes;
  14 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  15 import org.springframework.boot.SpringApplication;
  16 import org.springframework.context.ConfigurableApplicationContext;
  17 import org.springframework.stereotype.Component;
  18
  19 import javax.annotation.PostConstruct;
  20 import javax.annotation.PreDestroy;
  21 import java.net.URI;
  22 import java.util.Optional;
  23 import java.util.Properties;
  24 import java.util.concurrent.CompletableFuture;
  25
  26 import static org.apache.kafka.streams.errors.StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse.SHUTDOWN_CLIENT;
  27
  28
  29 @Slf4j
  30 @Component
  31 public class QueryStreamProcessor
  32 {
  33         public final KafkaStreams streams;
  34         public final HostInfo hostInfo;
  35         public final String storeName = "rankingsByUsername";
  36         public final StoreQueryParameters<ReadOnlyKeyValueStore<String, String>> storeParameters;
  37         public final ObjectMapper mapper;
  38
  39
  40         public QueryStreamProcessor(
  41                         QueryApplicationProperties properties,
  42                         ObjectMapper mapper,
  43                         ConfigurableApplicationContext context)
  44         {
  45                 StreamsBuilder builder = new StreamsBuilder();
  46
  47                 KTable<String, String> users = builder.table(properties.getUsersInputTopic());
  48                 KStream<String, String> rankings = builder.stream(properties.getRankingInputTopic());
  49
  50                 rankings
  51                                 .join(users, (rankingJson, userJson) ->
  52                                 {
  53                                         try
  54                                         {
  55                                                 Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
  56                                                 User user = mapper.readValue(userJson, User.class);
  57
  58                                                 return mapper.writeValueAsString(
  59                                                                 UserRanking.of(
  60                                                                                 user.getFirstName(),
  61                                                                                 user.getLastName(),
  62                                                                                 ranking.getEntries()));
  63                                         }
  64                                         catch (JsonProcessingException e)
  65                                         {
  66                                                 throw new RuntimeException(e);
  67                                         }
  68                                 })
  69                                 .toTable(Materialized.as(storeName));
  70
  71                 Properties props = new Properties();
  72                 props.put(StreamsConfig.APPLICATION_ID_CONFIG, properties.getApplicationId());
  73                 props.put(StreamsConfig.APPLICATION_SERVER_CONFIG, properties.getApplicationServer());
  74                 props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, properties.getBootstrapServer());
  75                 props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
  76                 props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
  77                 props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
  78
  79                 streams = new KafkaStreams(builder.build(), props);
  80                 streams.setUncaughtExceptionHandler((Throwable e) ->
  81                 {
  82                         log.error("Unexpected error!", e);
  83                         CompletableFuture.runAsync(() ->
  84                         {
  85                                 log.info("Stopping application...");
  86                                 SpringApplication.exit(context, () -> 1);
  87                         });
  88                         return SHUTDOWN_CLIENT;
  89                 });
  90
  91                 hostInfo = HostInfo.buildFromEndpoint(properties.getApplicationServer());
  92                 storeParameters = StoreQueryParameters.fromNameAndType(storeName, QueryableStoreTypes.keyValueStore());;
  93                 this.mapper = mapper;
  94         }
  95
  96         public Optional<URI> getRedirect(String username)
  97         {
  98                 KeyQueryMetadata metadata = streams.queryMetadataForKey(storeName, username, Serdes.String().serializer());
  99                 HostInfo activeHost = metadata.activeHost();
 100                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
 101
 102                 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
 103                 {
 104                         return Optional.empty();
 105                 }
 106
 107                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
 108                 log.debug("Redirecting to {}", location);
 109                 return Optional.of(location);
 110         }
 111
 112         public Optional<UserRanking> getUserRanking(String username)
 113         {
 114                 return
 115                                 Optional
 116                                                 .ofNullable(streams.store(storeParameters).get(username))
 117                                                 .map(json ->
 118                                                 {
 119                                                         try
 120                                                         {
 121                                                                 return mapper.readValue(json, UserRanking.class);
 122                                                         }
 123                                                         catch (JsonProcessingException e)
 124                                                         {
 125                                                                 throw new RuntimeException(e);
 126                                                         }
 127                                                 });
 128         }
 129
 130         @PostConstruct
 131         public void start()
 132         {
 133                 log.info("Starting Stream-Processor");
 134                 streams.start();
 135         }
 136
 137         @PreDestroy
 138         public void stop()
 139         {
 140                 log.info("Stopping Stream-Processor");
 141                 streams.close();
 142         }
 143 }