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.*;
   4 import lombok.extern.slf4j.Slf4j;
   5 import reactor.core.publisher.Flux;
   6 import reactor.core.publisher.Mono;
   7
   8 import java.util.HashSet;
   9 import java.util.Set;
  10 import java.util.UUID;
  11 import java.util.stream.Collectors;
  12
  13
  14 @Slf4j
  15 public class ShardedChatHome implements ChatHome
  16 {
  17   private final ChatHome[] chatHomes;
  18   private final Set<Integer> ownedShards;
  19   private final ShardingStrategy shardingStrategy;
  20
  21
  22   public  ShardedChatHome(
  23       ChatHome[] chatHomes,
  24       ShardingStrategy shardingStrategy)
  25   {
  26     this.chatHomes = chatHomes;
  27     this.shardingStrategy = shardingStrategy;
  28     this.ownedShards = new HashSet<>();
  29     for (int shard = 0; shard < chatHomes.length; shard++)
  30       if(chatHomes[shard] != null)
  31         this.ownedShards.add(shard);
  32     log.info(
  33         "Created ShardedChatHome for shards: {}",
  34         ownedShards
  35             .stream()
  36             .map(String::valueOf)
  37             .collect(Collectors.joining(", ")));
  38   }
  39
  40
  41   @Override
  42   public Mono<ChatRoomInfo> createChatRoom(UUID id, String name)
  43   {
  44     int shard = shardingStrategy.selectShard(id);
  45     return chatHomes[shard] == null
  46         ? Mono.error(new ShardNotOwnedException(shard))
  47         : chatHomes[shard].createChatRoom(id, name);
  48   }
  49
  50   @Override
  51   public Mono<ChatRoom> getChatRoom(UUID id)
  52   {
  53     int shard = selectShard(id);
  54     return chatHomes[shard] == null
  55         ? Mono.error(new ShardNotOwnedException(shard))
  56         : chatHomes[shard]
  57             .getChatRoom(id)
  58             .onErrorMap(throwable -> throwable instanceof UnknownChatroomException
  59             ? new UnknownChatroomException(
  60                 id,
  61                 shard,
  62                 ownedShards.stream().mapToInt(i -> i.intValue()).toArray())
  63             : throwable);
  64   }
  65
  66   @Override
  67   public Flux<ChatRoom> getChatRooms()
  68   {
  69     return Flux
  70         .fromIterable(ownedShards)
  71         .flatMap(shard -> chatHomes[shard].getChatRooms());
  72   }
  73
  74
  75   private int selectShard(UUID chatroomId)
  76   {
  77     return shardingStrategy.selectShard(chatroomId);
  78   }
  79 }