juplo.de Git - demos/kafka/deduplication/blob - src/main/java/de/juplo/demo/kafka/deduplication/Deduplicator.java

   1 package de.juplo.demo.kafka.deduplication;
   2
   3
   4 import org.apache.kafka.common.serialization.IntegerSerializer;
   5 import org.apache.kafka.common.serialization.Serdes;
   6 import org.apache.kafka.streams.*;
   7 import org.apache.kafka.streams.kstream.ValueTransformer;
   8 import org.apache.kafka.streams.kstream.ValueTransformerSupplier;
   9 import org.apache.kafka.streams.state.*;
  10 import org.slf4j.Logger;
  11 import org.slf4j.LoggerFactory;
  12 import org.springframework.boot.autoconfigure.web.ServerProperties;
  13 import org.springframework.http.HttpHeaders;
  14 import org.springframework.http.HttpStatus;
  15 import org.springframework.http.MediaType;
  16 import org.springframework.http.ResponseEntity;
  17 import org.springframework.web.bind.annotation.GetMapping;
  18 import org.springframework.web.bind.annotation.PathVariable;
  19 import org.springframework.web.bind.annotation.RestController;
  20
  21 import javax.annotation.PostConstruct;
  22 import javax.annotation.PreDestroy;
  23 import java.time.Duration;
  24 import java.util.Properties;
  25
  26
  27 @RestController
  28 public class Deduplicator
  29 {
  30   final static Logger LOG = LoggerFactory.getLogger(Deduplicator.class);
  31
  32   public final KafkaStreams streams;
  33   public final String host;
  34   public final int port;
  35
  36   public Deduplicator(
  37       ServerProperties serverProperties,
  38       StreamsHealthIndicator healthIndicator)
  39   {
  40     Properties properties = new Properties();
  41     properties.put("bootstrap.servers", "kafka:9092");
  42     properties.put("application.id", "streams-deduplicator");
  43     properties.put("default.key.serde", Serdes.StringSerde.class);
  44     properties.put("default.value.serde", Serdes.StringSerde.class);
  45
  46     this.host = serverProperties.getAddress().getHostAddress();
  47     this.port = serverProperties.getPort();
  48     properties.put("application.server", host + ":" + port);
  49
  50     streams = new KafkaStreams(Deduplicator.buildTopology(), properties);
  51     streams.setUncaughtExceptionHandler((Thread t, Throwable e) ->
  52     {
  53       LOG.error("Unexpected error in thread {}: {}", t, e.toString());
  54       try
  55       {
  56         streams.close(Duration.ofSeconds(5));
  57       }
  58       catch (Exception ex)
  59       {
  60         LOG.error("Could not close KafkaStreams!", ex);
  61       }
  62     });
  63     streams.setStateListener(healthIndicator);
  64   }
  65
  66   static Topology buildTopology()
  67   {
  68     StreamsBuilder builder = new StreamsBuilder();
  69
  70     // Create state-store for sequence numbers
  71     StoreBuilder<KeyValueStore<Integer,Long>> store =
  72         Stores.keyValueStoreBuilder(
  73             Stores.persistentKeyValueStore(DeduplicationTransformer.STORE),
  74             Serdes.Integer(),
  75             Serdes.Long());
  76     // register store
  77     builder.addStateStore(store);
  78
  79     builder
  80         .<String, String>stream("input")
  81         .flatTransformValues(
  82             new ValueTransformerSupplier<String, Iterable<String>>()
  83             {
  84               @Override
  85               public ValueTransformer<String, Iterable<String>> get()
  86               {
  87                 return new DeduplicationTransformer();
  88               }
  89             },
  90             DeduplicationTransformer.STORE)
  91         .to("output");
  92
  93     return builder.build();
  94   }
  95
  96   @GetMapping(path = "/watermark/{partition}", produces = MediaType.TEXT_PLAIN_VALUE)
  97   public ResponseEntity<String> getWatermarks(@PathVariable Integer partition)
  98   {
  99     KeyQueryMetadata metadata =
 100         streams.queryMetadataForKey(
 101             DeduplicationTransformer.STORE,
 102             partition, new IntegerSerializer());
 103
 104     if (metadata.getActiveHost().port() != port ||
 105         !metadata.getActiveHost().host().equals(host))
 106     {
 107       return
 108           ResponseEntity
 109               .status(HttpStatus.TEMPORARY_REDIRECT)
 110               .header(
 111                   HttpHeaders.LOCATION,
 112                   "http://" +
 113                       metadata.getActiveHost().host() +
 114                       ":" +
 115                       metadata.getActiveHost().port() +
 116                       "/watermark/" +
 117                       partition)
 118               .build();
 119     }
 120
 121     ReadOnlyKeyValueStore<Integer, Long> store = streams.store(
 122         StoreQueryParameters.fromNameAndType(
 123             DeduplicationTransformer.STORE,
 124             QueryableStoreTypes.keyValueStore()));
 125
 126     Long watermark = store.get(partition);
 127     if (watermark == null)
 128       return ResponseEntity.notFound().build();
 129
 130     return ResponseEntity.ok().body(watermark.toString());
 131   }
 132
 133
 134   @PostConstruct
 135   public void start()
 136   {
 137     streams.start();
 138   }
 139
 140   @PreDestroy
 141   public void stop()
 142   {
 143     streams.close(Duration.ofSeconds(5));
 144   }
 145 }