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 de.juplo.kafka.chat.backend.domain.exceptions.InvalidUsernameException;
   4 import de.juplo.kafka.chat.backend.domain.exceptions.MessageMutationException;
   5 import lombok.extern.slf4j.Slf4j;
   6 import reactor.core.publisher.Flux;
   7 import reactor.core.publisher.Mono;
   8 import reactor.core.publisher.Sinks;
   9 import reactor.core.publisher.SynchronousSink;
  10
  11 import java.time.Clock;
  12 import java.time.LocalDateTime;
  13 import java.util.regex.Matcher;
  14 import java.util.regex.Pattern;
  15
  16
  17 @Slf4j
  18 public class ChatRoomData
  19 {
  20   public final static Pattern VALID_USER = Pattern.compile("^[a-z0-9-]{2,}$");
  21
  22   private final ChatRoomService service;
  23   private final Clock clock;
  24   private final int bufferSize;
  25   private Sinks.Many<Message> sink;
  26
  27
  28   public ChatRoomData(
  29       Clock clock,
  30       ChatRoomService service,
  31       int bufferSize)
  32   {
  33     log.info("Created ChatRoom with buffer-size {}", bufferSize);
  34     this.clock = clock;
  35     this.service = service;
  36     this.bufferSize = bufferSize;
  37     // @RequiredArgsConstructor unfortunately not possible, because
  38     // the `bufferSize` is not set, if `createSink()` is called
  39     // from the variable declaration!
  40     this.sink = createSink();
  41   }
  42
  43
  44   synchronized public Mono<Message> addMessage(
  45       Long id,
  46       String user,
  47       String text)
  48   {
  49     Matcher matcher = VALID_USER.matcher(user);
  50     if (!matcher.matches())
  51       throw new InvalidUsernameException(user);
  52
  53     Message.MessageKey key = Message.MessageKey.of(user, id);
  54     return service
  55         .getMessage(key)
  56         .handle((Message existing, SynchronousSink<Message> sink) ->
  57         {
  58           if (existing.getMessageText().equals(text))
  59           {
  60             sink.next(existing);
  61           }
  62           else
  63           {
  64             sink.error(new MessageMutationException(existing, text));
  65           }
  66         })
  67         .switchIfEmpty(
  68             Mono
  69                 .defer(() -> service.persistMessage(key, LocalDateTime.now(clock), text))
  70                 .doOnNext(m ->
  71                 {
  72                   Sinks.EmitResult result = sink.tryEmitNext(m);
  73                   if (result.isFailure())
  74                   {
  75                     log.warn("Emitting of message failed with {} for {}", result.name(), m);
  76                   }
  77                 }));
  78   }
  79
  80
  81   public ChatRoomService getChatRoomService()
  82   {
  83     return service;
  84   }
  85
  86   public Mono<Message> getMessage(String username, Long messageId)
  87   {
  88     Message.MessageKey key = Message.MessageKey.of(username, messageId);
  89     return service.getMessage(key);
  90   }
  91
  92   synchronized public Flux<Message> listen()
  93   {
  94     return sink
  95         .asFlux()
  96         .doOnCancel(() -> sink = createSink()); // Sink hast to be recreated on auto-cancel!
  97   }
  98
  99   public Flux<Message> getMessages()
 100   {
 101     return getMessages(0, Long.MAX_VALUE);
 102   }
 103
 104   public Flux<Message> getMessages(long first, long last)
 105   {
 106     return service.getMessages(first, last);
 107   }
 108
 109   private Sinks.Many<Message> createSink()
 110   {
 111     return Sinks
 112         .many()
 113         .multicast()
 114         .onBackpressureBuffer(bufferSize);
 115   }
 116 }