juplo.de Git - demos/kafka/chat/blob - src/main/java/de/juplo/kafka/chat/backend/domain/ChatRoom.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.*;
  12 import java.util.regex.Matcher;
  13 import java.util.regex.Pattern;
  14
  15
  16 @Slf4j
  17 public class ChatRoom extends ChatRoomInfo
  18 {
  19   public final static Pattern VALID_USER = Pattern.compile("^[a-z0-9-]{2,}$");
  20   private final Clock clock;
  21   private final ChatRoomService service;
  22   private final int bufferSize;
  23   private Sinks.Many<Message> sink;
  24
  25
  26   public ChatRoom(
  27       UUID id,
  28       String name,
  29       int shard,
  30       Clock clock,
  31       ChatRoomService service,
  32       int bufferSize)
  33   {
  34     super(id, name, shard);
  35     log.info("Created ChatRoom {} with buffer-size {}", id, bufferSize);
  36     this.clock = clock;
  37     this.service = service;
  38     this.bufferSize = bufferSize;
  39     // @RequiredArgsConstructor unfortunately not possible, because
  40     // the `bufferSize` is not set, if `createSink()` is called
  41     // from the variable declaration!
  42     this.sink = createSink();
  43   }
  44
  45
  46   synchronized public Mono<Message> addMessage(
  47       Long id,
  48       String user,
  49       String text)
  50   {
  51     Matcher matcher = VALID_USER.matcher(user);
  52     if (!matcher.matches())
  53       throw new InvalidUsernameException(user);
  54
  55     Message.MessageKey key = Message.MessageKey.of(user, id);
  56     return service
  57         .getMessage(key)
  58         .handle((Message existing, SynchronousSink<Message> sink) ->
  59         {
  60           if (existing.getMessageText().equals(text))
  61           {
  62             sink.next(existing);
  63           }
  64           else
  65           {
  66             sink.error(new MessageMutationException(existing, text));
  67           }
  68         })
  69         .switchIfEmpty(
  70             Mono
  71                 .defer(() -> service.persistMessage(key, LocalDateTime.now(clock), text))
  72                 .doOnNext(m ->
  73                 {
  74                   Sinks.EmitResult result = sink.tryEmitNext(m);
  75                   if (result.isFailure())
  76                   {
  77                     log.warn("Emitting of message failed with {} for {}", result.name(), m);
  78                   }
  79                 }));
  80   }
  81
  82
  83   public ChatRoomService getChatRoomService()
  84   {
  85     return service;
  86   }
  87
  88   public Mono<Message> getMessage(String username, Long messageId)
  89   {
  90     Message.MessageKey key = Message.MessageKey.of(username, messageId);
  91     return service.getMessage(key);
  92   }
  93
  94   synchronized public Flux<Message> listen()
  95   {
  96     return sink
  97         .asFlux()
  98         .doOnCancel(() -> sink = createSink()); // Sink hast to be recreated on auto-cancel!
  99   }
 100
 101   public Flux<Message> getMessages()
 102   {
 103     return getMessages(0, Long.MAX_VALUE);
 104   }
 105
 106   public Flux<Message> getMessages(long first, long last)
 107   {
 108     return service.getMessages(first, last);
 109   }
 110
 111   private Sinks.Many<Message> createSink()
 112   {
 113     return Sinks
 114         .many()
 115         .multicast()
 116         .onBackpressureBuffer(bufferSize);
 117   }
 118 }