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 jakarta.annotation.PostConstruct;
   6 import jakarta.annotation.PreDestroy;
   7 import lombok.extern.slf4j.Slf4j;
   8 import org.apache.kafka.common.serialization.Serdes;
   9 import org.apache.kafka.streams.KafkaStreams;
  10 import org.apache.kafka.streams.KeyQueryMetadata;
  11 import org.apache.kafka.streams.StoreQueryParameters;
  12 import org.apache.kafka.streams.StreamsBuilder;
  13 import org.apache.kafka.streams.kstream.KStream;
  14 import org.apache.kafka.streams.kstream.KTable;
  15 import org.apache.kafka.streams.kstream.Materialized;
  16 import org.apache.kafka.streams.state.HostInfo;
  17 import org.apache.kafka.streams.state.QueryableStoreTypes;
  18 import org.apache.kafka.streams.state.ReadOnlyKeyValueStore;
  19 import org.springframework.boot.SpringApplication;
  20 import org.springframework.context.ConfigurableApplicationContext;
  21
  22 import java.net.URI;
  23 import java.util.Optional;
  24 import java.util.Properties;
  25 import java.util.concurrent.CompletableFuture;
  26
  27 import static org.apache.kafka.streams.errors.StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse.SHUTDOWN_CLIENT;
  28
  29
  30 @Slf4j
  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                         Properties props,
  42                         HostInfo applicationServer,
  43                         String usersInputTopic,
  44                         String rankingInputTopic,
  45                         ObjectMapper mapper,
  46                         ConfigurableApplicationContext context)
  47         {
  48                 StreamsBuilder builder = new StreamsBuilder();
  49
  50                 KTable<String, String> users = builder.table(usersInputTopic);
  51                 KStream<String, String> rankings = builder.stream(rankingInputTopic);
  52
  53                 rankings
  54                                 .join(users, (rankingJson, userJson) ->
  55                                 {
  56                                         try
  57                                         {
  58                                                 Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
  59                                                 User user = mapper.readValue(userJson, User.class);
  60
  61                                                 return mapper.writeValueAsString(
  62                                                                 UserRanking.of(
  63                                                                                 user.getFirstName(),
  64                                                                                 user.getLastName(),
  65                                                                                 ranking.getEntries()));
  66                                         }
  67                                         catch (JsonProcessingException e)
  68                                         {
  69                                                 throw new RuntimeException(e);
  70                                         }
  71                                 })
  72                                 .toTable(Materialized.as(storeName));
  73
  74                 streams = new KafkaStreams(builder.build(), props);
  75                 streams.setUncaughtExceptionHandler((Throwable e) ->
  76                 {
  77                         log.error("Unexpected error!", e);
  78                         CompletableFuture.runAsync(() ->
  79                         {
  80                                 log.info("Stopping application...");
  81                                 SpringApplication.exit(context, () -> 1);
  82                         });
  83                         return SHUTDOWN_CLIENT;
  84                 });
  85
  86                 hostInfo = applicationServer;
  87                 storeParameters = StoreQueryParameters.fromNameAndType(storeName, QueryableStoreTypes.keyValueStore());;
  88                 this.mapper = mapper;
  89         }
  90
  91         public Optional<URI> getRedirect(String username)
  92         {
  93                 KeyQueryMetadata metadata = streams.queryMetadataForKey(storeName, username, Serdes.String().serializer());
  94                 HostInfo activeHost = metadata.activeHost();
  95                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
  96
  97                 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
  98                 {
  99                         return Optional.empty();
 100                 }
 101
 102                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
 103                 log.debug("Redirecting to {}", location);
 104                 return Optional.of(location);
 105         }
 106
 107         public Optional<UserRanking> getUserRanking(String username)
 108         {
 109                 return
 110                                 Optional
 111                                                 .ofNullable(streams.store(storeParameters).get(username))
 112                                                 .map(json ->
 113                                                 {
 114                                                         try
 115                                                         {
 116                                                                 return mapper.readValue(json, UserRanking.class);
 117                                                         }
 118                                                         catch (JsonProcessingException e)
 119                                                         {
 120                                                                 throw new RuntimeException(e);
 121                                                         }
 122                                                 });
 123         }
 124
 125         @PostConstruct
 126         public void start()
 127         {
 128                 log.info("Starting Stream-Processor");
 129                 streams.start();
 130         }
 131
 132         @PreDestroy
 133         public void stop()
 134         {
 135                 log.info("Stopping Stream-Processor");
 136                 streams.close();
 137         }
 138 }