juplo.de Git - demos/kafka/chat/blob - src/main/java/de/juplo/kafka/chat/backend/persistence/kafka/KafkaChatHome.java

   1 package de.juplo.kafka.chat.backend.persistence.kafka;
   2
   3 import de.juplo.kafka.chat.backend.domain.ChatHome;
   4 import de.juplo.kafka.chat.backend.domain.ChatRoom;
   5 import de.juplo.kafka.chat.backend.domain.UnknownChatroomException;
   6 import lombok.RequiredArgsConstructor;
   7 import lombok.extern.slf4j.Slf4j;
   8 import org.apache.kafka.common.utils.Utils;
   9 import reactor.core.publisher.Flux;
  10 import reactor.core.publisher.Mono;
  11
  12 import java.util.*;
  13
  14
  15 @RequiredArgsConstructor
  16 @Slf4j
  17 public class KafkaChatHome implements ChatHome
  18 {
  19   private final int numPartitions;
  20   private final ChatRoomChannel chatRoomChannel;
  21
  22
  23   @Override
  24   public Mono<ChatRoom> getChatRoom(UUID id)
  25   {
  26     int shard = selectShard(id);
  27     return chatRoomChannel
  28         .getChatRoom(shard, id)
  29         .switchIfEmpty(Mono.error(() -> new UnknownChatroomException(id)));
  30   }
  31
  32   int selectShard(UUID chatRoomId)
  33   {
  34     byte[] serializedKey = chatRoomId.toString().getBytes();
  35     return Utils.toPositive(Utils.murmur2(serializedKey)) % numPartitions;
  36   }
  37
  38   @Override
  39   public Flux<ChatRoom> getChatRooms()
  40   {
  41       return chatRoomChannel.getChatRooms();
  42   }
  43 }