juplo.de Git - demos/kafka/chat/blob - src/main/java/de/juplo/kafka/chat/backend/domain/ChatRoomData.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 import reactor.core.publisher.Sinks;
   7 import reactor.core.publisher.SynchronousSink;
   8
   9 import java.time.Clock;
  10 import java.time.LocalDateTime;
  11 import java.util.regex.Matcher;
  12 import java.util.regex.Pattern;
  13
  14
  15 @Slf4j
  16 public class ChatRoomData
  17 {
  18   public final static Pattern VALID_USER = Pattern.compile("^[a-z0-9-]{2,}$");
  19
  20   private final ChatRoomService service;
  21   private final Clock clock;
  22   private final int bufferSize;
  23   private Sinks.Many<Message> sink;
  24
  25
  26   public ChatRoomData(
  27       Clock clock,
  28       ChatRoomService service,
  29       int bufferSize)
  30   {
  31     log.info("Created ChatRoom with buffer-size {}", bufferSize);
  32     this.clock = clock;
  33     this.service = service;
  34     this.bufferSize = bufferSize;
  35     // @RequiredArgsConstructor unfortunately not possible, because
  36     // the `bufferSize` is not set, if `createSink()` is called
  37     // from the variable declaration!
  38     this.sink = createSink();
  39   }
  40
  41
  42   synchronized public Mono<Message> addMessage(
  43       Long id,
  44       String user,
  45       String text)
  46   {
  47     Matcher matcher = VALID_USER.matcher(user);
  48     if (!matcher.matches())
  49       throw new InvalidUsernameException(user);
  50
  51     Message.MessageKey key = Message.MessageKey.of(user, id);
  52     return service
  53         .getMessage(key)
  54         .handle((Message existing, SynchronousSink<Message> sink) ->
  55         {
  56           if (existing.getMessageText().equals(text))
  57           {
  58             sink.next(existing);
  59           }
  60           else
  61           {
  62             sink.error(new MessageMutationException(existing, text));
  63           }
  64         })
  65         .switchIfEmpty(
  66             Mono
  67                 .defer(() -> service.persistMessage(key, LocalDateTime.now(clock), text))
  68                 .doOnNext(m ->
  69                 {
  70                   Sinks.EmitResult result = sink.tryEmitNext(m);
  71                   if (result.isFailure())
  72                   {
  73                     log.warn("Emitting of message failed with {} for {}", result.name(), m);
  74                   }
  75                 }));
  76   }
  77
  78
  79   public ChatRoomService getChatRoomService()
  80   {
  81     return service;
  82   }
  83
  84   public Mono<Message> getMessage(String username, Long messageId)
  85   {
  86     Message.MessageKey key = Message.MessageKey.of(username, messageId);
  87     return service.getMessage(key);
  88   }
  89
  90   synchronized public Flux<Message> listen()
  91   {
  92     return sink
  93         .asFlux()
  94         .doOnCancel(() -> sink = createSink()); // Sink hast to be recreated on auto-cancel!
  95   }
  96
  97   public Flux<Message> getMessages()
  98   {
  99     return getMessages(0, Long.MAX_VALUE);
 100   }
 101
 102   public Flux<Message> getMessages(long first, long last)
 103   {
 104     return service.getMessages(first, last);
 105   }
 106
 107   private Sinks.Many<Message> createSink()
 108   {
 109     return Sinks
 110         .many()
 111         .multicast()
 112         .onBackpressureBuffer(bufferSize);
 113   }
 114 }