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
  18 import javax.annotation.PostConstruct;
  19 import javax.annotation.PreDestroy;
  20 import java.net.URI;
  21 import java.util.Optional;
  22 import java.util.Properties;
  23 import java.util.concurrent.CompletableFuture;
  24
  25 import static org.apache.kafka.streams.errors.StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse.SHUTDOWN_CLIENT;
  26
  27
  28 @Slf4j
  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                         String applicationId,
  40                         HostInfo applicationServer,
  41                         String bootstrapServer,
  42                         String usersInputTopic,
  43                         String rankingInputTopic,
  44                         ObjectMapper mapper,
  45                         ConfigurableApplicationContext context)
  46         {
  47                 StreamsBuilder builder = new StreamsBuilder();
  48
  49                 KTable<String, String> users = builder.table(usersInputTopic);
  50                 KStream<String, String> rankings = builder.stream(rankingInputTopic);
  51
  52                 rankings
  53                                 .join(users, (rankingJson, userJson) ->
  54                                 {
  55                                         try
  56                                         {
  57                                                 Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
  58                                                 User user = mapper.readValue(userJson, User.class);
  59
  60                                                 return mapper.writeValueAsString(
  61                                                                 UserRanking.of(
  62                                                                                 user.getFirstName(),
  63                                                                                 user.getLastName(),
  64                                                                                 ranking.getEntries()));
  65                                         }
  66                                         catch (JsonProcessingException e)
  67                                         {
  68                                                 throw new RuntimeException(e);
  69                                         }
  70                                 })
  71                                 .toTable(Materialized.as(storeName));
  72
  73                 Properties props = new Properties();
  74                 props.put(StreamsConfig.APPLICATION_ID_CONFIG, applicationId);
  75                 props.put(StreamsConfig.APPLICATION_SERVER_CONFIG, applicationServer.host() + ":" + applicationServer.port());
  76                 props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, bootstrapServer);
  77                 props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
  78                 props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
  79                 props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
  80
  81                 streams = new KafkaStreams(builder.build(), props);
  82                 streams.setUncaughtExceptionHandler((Throwable e) ->
  83                 {
  84                         log.error("Unexpected error!", e);
  85                         CompletableFuture.runAsync(() ->
  86                         {
  87                                 log.info("Stopping application...");
  88                                 SpringApplication.exit(context, () -> 1);
  89                         });
  90                         return SHUTDOWN_CLIENT;
  91                 });
  92
  93                 hostInfo = applicationServer;
  94                 storeParameters = StoreQueryParameters.fromNameAndType(storeName, QueryableStoreTypes.keyValueStore());;
  95                 this.mapper = mapper;
  96         }
  97
  98         public Optional<URI> getRedirect(String username)
  99         {
 100                 KeyQueryMetadata metadata = streams.queryMetadataForKey(storeName, username, Serdes.String().serializer());
 101                 HostInfo activeHost = metadata.activeHost();
 102                 log.debug("Local store for {}: {}, {}:{}", username, metadata.partition(), activeHost.host(), activeHost.port());
 103
 104                 if (activeHost.equals(this.hostInfo) || activeHost.equals(HostInfo.unavailable()))
 105                 {
 106                         return Optional.empty();
 107                 }
 108
 109                 URI location = URI.create("http://" + activeHost.host() + ":" + activeHost.port() + "/" + username);
 110                 log.debug("Redirecting to {}", location);
 111                 return Optional.of(location);
 112         }
 113
 114         public Optional<UserRanking> getUserRanking(String username)
 115         {
 116                 return
 117                                 Optional
 118                                                 .ofNullable(streams.store(storeParameters).get(username))
 119                                                 .map(json ->
 120                                                 {
 121                                                         try
 122                                                         {
 123                                                                 return mapper.readValue(json, UserRanking.class);
 124                                                         }
 125                                                         catch (JsonProcessingException e)
 126                                                         {
 127                                                                 throw new RuntimeException(e);
 128                                                         }
 129                                                 });
 130         }
 131
 132         @PostConstruct
 133         public void start()
 134         {
 135                 log.info("Starting Stream-Processor");
 136                 streams.start();
 137         }
 138
 139         @PreDestroy
 140         public void stop()
 141         {
 142                 log.info("Stopping Stream-Processor");
 143                 streams.close();
 144         }
 145 }