Merge pull request #526 from danthe1st/fix-startup

fix exception while loading message cache on startup

Author: danthe1st

src/main/java/net/discordjug/javabot/data/h2db/message_cache/MessageCache.java

@@ -83,16 +83,23 @@ public MessageCache(BotConfig botConfig, MessageCacheRepository cacheRepository,
 	}
 
 	/**
-	 * Synchronizes Messages saved in the Database with what is currently stored in memory.
+	 * Synchronizes Messages saved in the Database with what is currently stored in memory. This action is executed in the background.
 	 */
 	public void synchronize() {
 		asyncPool.execute(()->{
-			cacheRepository.delete(cache.size());
-			cacheRepository.insertList(new ArrayList<>(cache));
-			messageCount = 0;
-			log.info("Synchronized Database with local Cache.");
+			synchronizeNow();
 		});
 	}
+	
+	/**
+	 * Synchronizes Messages saved in the Database with what is currently stored in memory and wait until the synchronization finishes.
+	 */
+	public void synchronizeNow() {
+		cacheRepository.delete(cache.size());
+		cacheRepository.insertList(new ArrayList<>(cache));
+		messageCount = 0;
+		log.info("Synchronized Database with local Cache.");
+	}
 
 	/**
 	 * Caches a single {@link Message} object.

src/main/java/net/discordjug/javabot/data/h2db/message_cache/dao/MessageCacheRepository.java

@@ -82,13 +82,14 @@ public int getBatchSize() {
 	public List<CachedMessage> getAll() throws DataAccessException {
 		List<CachedMessage> messagesWithLink = jdbcTemplate.query(
 				"SELECT * FROM message_cache LEFT JOIN message_cache_attachments ON message_cache.message_id = message_cache_attachments.message_id",
-				(rs, rowNum) -> this.read(rs));
+				(rs, _) -> this.read(rs));
 		Map<Long, CachedMessage> messages=new LinkedHashMap<>();
 		for (CachedMessage msg : messagesWithLink) {
-			CachedMessage previous = messages.putIfAbsent(msg.getMessageId(), msg);
-			if(previous!=null) {
-				previous.getAttachments().addAll(msg.getAttachments());
-			}
+			messages.merge(msg.getMessageId(), msg, (oldValue, value) -> {
+				ArrayList<String> attachments = new ArrayList<>(oldValue.getAttachments());
+				attachments.addAll(value.getAttachments());
+				return new CachedMessage(oldValue.getMessageId(), oldValue.getAuthorId(), oldValue.getMessageContent(), attachments);
+			});
 		}
 		return new ArrayList<>(messages.values());
 	}

src/main/java/net/discordjug/javabot/systems/staff_commands/RedeployCommand.java

@@ -63,7 +63,7 @@ public void execute(@NotNull SlashCommandInteractionEvent event) {
 		}
 		log.warn("Redeploying... Requested by: " + UserUtils.getUserTag(event.getUser()));
 		event.reply("**Redeploying...** This may take some time.").queue();
-		messageCache.synchronize();
+		messageCache.synchronizeNow();
 		asyncPool.shutdownNow();
 		try {
 			asyncPool.awaitTermination(3, TimeUnit.SECONDS);