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.apache.kafka.streams.*;
import org.apache.kafka.streams.kstream.Consumed;
+import org.apache.kafka.streams.kstream.Grouped;
+import org.apache.kafka.streams.kstream.Materialized;
+import org.apache.kafka.streams.kstream.Produced;
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.Arrays;
+import java.util.LinkedList;
+import java.util.List;
import java.util.Properties;
import java.util.concurrent.CompletableFuture;
import java.util.regex.Pattern;
StreamsBuilder builder = new StreamsBuilder();
builder
- .<Key, Long>stream(properties.getInputTopic(), Consumed.with(SpecificAvroSerializer.class, Serdes.String()) )
+ .<Key, Long>stream(properties.getInputTopic(), Consumed.with(null, Serdes.Long()))
.map((key, count) -> new KeyValue<>(
key.getUsername(),
Entry.newBuilder().setWord(key.getWord()).setCount(count).build()))
- .groupByKey()
+ .groupByKey(Grouped.keySerde(Serdes.String()))
.aggregate(
- () -> Ranking.newBuilder().build(),
- (username, entry, ranking) -> {
- ranking.getEntries().add(entry);
+ () -> Ranking.newBuilder().setEntries(new LinkedList<Entry>()).build(),
+ (username, newEntry, ranking) -> {
+ List<Entry> entries = new LinkedList<>(ranking.getEntries());
+
+ if (entries.isEmpty())
+ {
+ entries.add(newEntry);
+ }
+ else
+ {
+ for (int i = 0; i < entries.size(); i++)
+ {
+ Entry entry = entries.get(i);
+ if (entry.getCount() <= newEntry.getCount())
+ {
+ entries.add(i, newEntry);
+ for (int j = i + 1; j < entries.size(); j++)
+ {
+ entry = entries.get(j);
+ if (entry.getWord().equals(newEntry.getWord()))
+ {
+ entries.remove(j);
+ break;
+ }
+ }
+ if (entries.size() > 10)
+ {
+ entries = entries.subList(0, 10);
+ }
+ }
+ }
+ }
+
+ ranking.setEntries(entries);
return ranking;
})
.toStream()
- .to(properties.getOutputTopic());
+ .to(properties.getOutputTopic(), Produced.keySerde(Serdes.String()));
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());
+ props.put(StreamsConfig.DEFAULT_KEY_SERDE_CLASS_CONFIG, SpecificAvroSerde.class);
props.put(StreamsConfig.DEFAULT_VALUE_SERDE_CLASS_CONFIG, SpecificAvroSerde.class);
props.put(AbstractKafkaSchemaSerDeConfig.SCHEMA_REGISTRY_URL_CONFIG, properties.getSchemaRegistry());
props.put(ConsumerConfig.AUTO_OFFSET_RESET_CONFIG, "earliest");
- streams = new KafkaStreams(builder.build(), props);
+ Topology topology = builder.build();
+ log.info("Topology:\n-----------------\n\n{}-----------------", topology.describe());
+
+ streams = new KafkaStreams(topology, props);
streams.setUncaughtExceptionHandler((Throwable e) ->
{
log.error("Unexpected error!", e);