top10:1.0.0 - ranks first 10 mostly used words, keyed by user

[demos/kafka/wordcount] / src / main / java / de / juplo / kafka / wordcount / top10 / Top10StreamProcessor.java

diff --git a/src/main/java/de/juplo/kafka/wordcount/top10/Top10StreamProcessor.java b/src/main/java/de/juplo/kafka/wordcount/top10/Top10StreamProcessor.java
new file mode 100644 (file)
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+++ b/src/main/java/de/juplo/kafka/wordcount/top10/Top10StreamProcessor.java
@@ -0,0 +1,111 @@
+package de.juplo.kafka.wordcount.top10;
+
+import com.fasterxml.jackson.core.JsonProcessingException;
+import com.fasterxml.jackson.databind.ObjectMapper;
+import lombok.extern.slf4j.Slf4j;
+import org.apache.kafka.clients.consumer.ConsumerConfig;
+import org.apache.kafka.common.serialization.Serdes;
+import org.apache.kafka.streams.KafkaStreams;
+import org.apache.kafka.streams.KeyValue;
+import org.apache.kafka.streams.StreamsBuilder;
+import org.apache.kafka.streams.StreamsConfig;
+import org.springframework.boot.SpringApplication;
+import org.springframework.context.ConfigurableApplicationContext;
+import org.springframework.stereotype.Component;
+
+import javax.annotation.PostConstruct;
+import javax.annotation.PreDestroy;
+import java.util.Properties;
+import java.util.concurrent.CompletableFuture;
+import java.util.regex.Pattern;
+
+import static org.apache.kafka.streams.errors.StreamsUncaughtExceptionHandler.StreamThreadExceptionResponse.SHUTDOWN_CLIENT;
+
+
+@Slf4j
+@Component
+public class Top10StreamProcessor
+{
+       final static Pattern PATTERN = Pattern.compile("\\W+");
+
+       public final KafkaStreams streams;
+
+
+       public Top10StreamProcessor(
+                       Top10ApplicationProperties properties,
+                       ObjectMapper mapper,
+                       ConfigurableApplicationContext context)
+       {
+               StreamsBuilder builder = new StreamsBuilder();
+
+               builder
+                               .<String, String>stream(properties.getInputTopic())
+                               .map((keyJson, countStr) ->
+                               {
+                                       try
+                                       {
+                                               Key key = mapper.readValue(keyJson, Key.class);
+                                               Long count = Long.parseLong(countStr);
+                                               Entry entry = Entry.of(key.getWord(), count);
+                                               String entryJson = mapper.writeValueAsString(entry);
+                                               return new KeyValue<>(key.getUsername(), entryJson);
+                                       }
+                                       catch (JsonProcessingException e)
+                                       {
+                                               throw new RuntimeException(e);
+                                       }
+                               })
+                               .groupByKey()
+                               .aggregate(
+                                               () -> "{\"entries\"     : []}",
+                                               (username, entryJson, rankingJson) ->
+                                               {
+                                                       try
+                                                       {
+                                                               Ranking ranking = mapper.readValue(rankingJson, Ranking.class);
+                                                               ranking.add(mapper.readValue(entryJson, Entry.class));
+                                                               return mapper.writeValueAsString(ranking);
+                                                       }
+                                                       catch (JsonProcessingException e)
+                                                       {
+                                                               throw new RuntimeException(e);
+                                                       }
+                                               }
+                               )
+                               .toStream()
+                               .to(properties.getOutputTopic());
+
+               Properties props = new Properties();
+               props.put(StreamsConfig.APPLICATION_ID_CONFIG, properties.getApplicationId());
+               props.put(StreamsConfig.BOOTSTRAP_SERVERS_CONFIG, properties.getBootstrapServer());
+               props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
+               props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, Serdes.String().getClass().getName());
+               props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
+
+               streams = new KafkaStreams(builder.build(), props);
+               streams.setUncaughtExceptionHandler((Throwable e) ->
+               {
+                       log.error("Unexpected error!", e);
+                       CompletableFuture.runAsync(() ->
+                       {
+                               log.info("Stopping application...");
+                               SpringApplication.exit(context, () -> 1);
+                       });
+                       return SHUTDOWN_CLIENT;
+               });
+       }
+
+       @PostConstruct
+       public void start()
+       {
+               log.info("Starting Stream-Processor");
+               streams.start();
+       }
+
+       @PreDestroy
+       public void stop()
+       {
+               log.info("Stopping Stream-Processor");
+               streams.close();
+       }
+}