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

   1 package de.juplo.kafka.chat.backend.persistence.inmemory;
   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.ShardNotOwnedException;
   6 import lombok.extern.slf4j.Slf4j;
   7 import reactor.core.publisher.Flux;
   8 import reactor.core.publisher.Mono;
   9
  10 import java.util.HashSet;
  11 import java.util.Set;
  12 import java.util.UUID;
  13 import java.util.stream.Collectors;
  14
  15
  16 @Slf4j
  17 public class ShardedChatHome implements ChatHome
  18 {
  19   private final ChatHome[] chatHomes;
  20   private final Set<Integer> ownedShards;
  21   private final ShardingStrategy shardingStrategy;
  22
  23
  24   public  ShardedChatHome(
  25       ChatHome[] chatHomes,
  26       ShardingStrategy shardingStrategy)
  27   {
  28     this.chatHomes = chatHomes;
  29     this.shardingStrategy = shardingStrategy;
  30     this.ownedShards = new HashSet<>();
  31     for (int shard = 0; shard < chatHomes.length; shard++)
  32       if(chatHomes[shard] != null)
  33         this.ownedShards.add(shard);
  34     log.info(
  35         "Created ShardedChatHome for shards: {}",
  36         ownedShards
  37             .stream()
  38             .map(String::valueOf)
  39             .collect(Collectors.joining(", ")));
  40   }
  41
  42
  43   @Override
  44   public Mono<ChatRoom> getChatRoom(UUID id)
  45   {
  46     int shard = selectShard(id);
  47     return chatHomes[shard] == null
  48         ? Mono.error(new ShardNotOwnedException(shard))
  49         : chatHomes[shard].getChatRoom(id);
  50   }
  51
  52   @Override
  53   public Flux<ChatRoom> getChatRooms()
  54   {
  55     return Flux
  56         .fromIterable(ownedShards)
  57         .flatMap(shard -> chatHomes[shard].getChatRooms());
  58   }
  59
  60
  61   private int selectShard(UUID chatroomId)
  62   {
  63     return shardingStrategy.selectShard(chatroomId);
  64   }
  65 }