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.domain;
   2
   3 import lombok.extern.slf4j.Slf4j;
   4 import reactor.core.publisher.Flux;
   5 import reactor.core.publisher.Mono;
   6
   7 import java.util.HashSet;
   8 import java.util.Set;
   9 import java.util.UUID;
  10 import java.util.stream.Collectors;
  11
  12
  13 @Slf4j
  14 public class ShardedChatHome implements ChatHome
  15 {
  16   private final ChatHome[] chatHomes;
  17   private final Set<Integer> ownedShards;
  18   private final ShardingStrategy shardingStrategy;
  19
  20
  21   public  ShardedChatHome(
  22       ChatHome[] chatHomes,
  23       ShardingStrategy shardingStrategy)
  24   {
  25     this.chatHomes = chatHomes;
  26     this.shardingStrategy = shardingStrategy;
  27     this.ownedShards = new HashSet<>();
  28     for (int shard = 0; shard < chatHomes.length; shard++)
  29       if(chatHomes[shard] != null)
  30         this.ownedShards.add(shard);
  31     log.info(
  32         "Created ShardedChatHome for shards: {}",
  33         ownedShards
  34             .stream()
  35             .map(String::valueOf)
  36             .collect(Collectors.joining(", ")));
  37   }
  38
  39
  40   @Override
  41   public Mono<ChatRoom> getChatRoom(UUID id)
  42   {
  43     int shard = selectShard(id);
  44     if (chatHomes[shard] == null)
  45       throw new ShardNotOwnedException(shard);
  46     return chatHomes[shard].getChatRoom(id);
  47   }
  48
  49   @Override
  50   public Flux<ChatRoom> getChatRooms()
  51   {
  52     return Flux
  53         .fromIterable(ownedShards)
  54         .flatMap(shard -> chatHomes[shard].getChatRooms());
  55   }
  56
  57
  58   private int selectShard(UUID chatroomId)
  59   {
  60     return shardingStrategy.selectShard(chatroomId);
  61   }
  62 }