refactor: Pulled business-logic into class `ShardedChatHome`

[demos/kafka/chat] / src / main / java / de / juplo / kafka / chat / backend / persistence / KafkaLikeShardingStrategy.java

diff --git a/src/main/java/de/juplo/kafka/chat/backend/persistence/KafkaLikeShardingStrategy.java b/src/main/java/de/juplo/kafka/chat/backend/persistence/KafkaLikeShardingStrategy.java
new file mode 100644 (file)
index 0000000..41fd9cd
--- /dev/null
+++ b/src/main/java/de/juplo/kafka/chat/backend/persistence/KafkaLikeShardingStrategy.java
@@ -0,0 +1,21 @@
+package de.juplo.kafka.chat.backend.persistence;
+
+import de.juplo.kafka.chat.backend.domain.ShardingStrategy;
+import lombok.RequiredArgsConstructor;
+import org.apache.kafka.common.utils.Utils;
+
+import java.util.UUID;
+
+
+@RequiredArgsConstructor
+public class KafkaLikeShardingStrategy implements ShardingStrategy
+{
+  private final int numPartitions;
+
+  @Override
+  public int selectShard(UUID chatRoomId)
+  {
+    byte[] serializedKey = chatRoomId.toString().getBytes();
+    return Utils.toPositive(Utils.murmur2(serializedKey)) % numPartitions;
+  }
+}