Optimize DefaultUserDestinationResolver.resolveDestination()

Issue: SPR-15602

spring-messaging/src/main/java/org/springframework/messaging/simp/user/DefaultUserDestinationResolver.java

@@ -121,12 +121,12 @@ public class DefaultUserDestinationResolver implements UserDestinationResolver {
 
 	@Override
 	public UserDestinationResult resolveDestination(Message<?> message) {
-		String sourceDestination = SimpMessageHeaderAccessor.getDestination(message.getHeaders());
 		ParseResult parseResult = parse(message);
 		if (parseResult == null) {
 			return null;
 		}
 		String user = parseResult.getUser();
+		String sourceDestination = parseResult.getSourceDestination();
 		Set<String> targetSet = new HashSet<>();
 		for (String sessionId : parseResult.getSessionIds()) {
 			String actualDestination = parseResult.getActualDestination();
@@ -142,65 +142,81 @@ public class DefaultUserDestinationResolver implements UserDestinationResolver {
 	@Nullable
 	private ParseResult parse(Message<?> message) {
 		MessageHeaders headers = message.getHeaders();
-		String destination = SimpMessageHeaderAccessor.getDestination(headers);
-		if (destination == null || !checkDestination(destination, this.prefix)) {
+		String sourceDestination = SimpMessageHeaderAccessor.getDestination(headers);
+		if (sourceDestination == null || !checkDestination(sourceDestination, this.prefix)) {
 			return null;
 		}
 		SimpMessageType messageType = SimpMessageHeaderAccessor.getMessageType(headers);
+		switch (messageType) {
+			case SUBSCRIBE:
+			case UNSUBSCRIBE:
+				return parseSubscriptionMessage(message, headers, sourceDestination);
+			case MESSAGE:
+				return parseMessage(headers, sourceDestination);
+			default:
+				return null;
+		}
+	}
+
+	private ParseResult parseSubscriptionMessage(Message<?> message, MessageHeaders headers, String sourceDestination) {
+		String sessionId = SimpMessageHeaderAccessor.getSessionId(headers);
+		if (sessionId == null) {
+			logger.error("No session id. Ignoring " + message);
+			return null;
+		}
+		int prefixEnd = this.prefix.length() - 1;
+		String actualDestination = sourceDestination.substring(prefixEnd);
+		if (!this.keepLeadingSlash) {
+			actualDestination = actualDestination.substring(1);
+		}
 		Principal principal = SimpMessageHeaderAccessor.getUser(headers);
+		String user = (principal != null ? principal.getName() : null);
+		Set<String> sessionIds = Collections.singleton(sessionId);
+		return new ParseResult(sourceDestination, actualDestination, sourceDestination, sessionIds, user);
+	}
+
+	private ParseResult parseMessage(MessageHeaders headers, String sourceDestination) {
+		int prefixEnd = this.prefix.length();
+		int userEnd = sourceDestination.indexOf('/', prefixEnd);
+		Assert.isTrue(userEnd > 0, "Expected destination pattern \"/user/{userId}/**\"");
+		String actualDestination = sourceDestination.substring(userEnd);
+		String subscribeDestination = this.prefix.substring(0, prefixEnd - 1) + actualDestination;
+		String userName = sourceDestination.substring(prefixEnd, userEnd);
+		userName = StringUtils.replace(userName, "%2F", "/");
 		String sessionId = SimpMessageHeaderAccessor.getSessionId(headers);
-		if (SimpMessageType.SUBSCRIBE.equals(messageType) || SimpMessageType.UNSUBSCRIBE.equals(messageType)) {
-			if (sessionId == null) {
-				logger.error("No session id. Ignoring " + message);
-				return null;
-			}
-			int prefixEnd = this.prefix.length() - 1;
-			String actualDestination = destination.substring(prefixEnd);
-			if (!this.keepLeadingSlash) {
-				actualDestination = actualDestination.substring(1);
-			}
-			String user = (principal != null ? principal.getName() : null);
-			return new ParseResult(actualDestination, destination, Collections.singleton(sessionId), user);
+		Set<String> sessionIds;
+		if (userName.equals(sessionId)) {
+			userName = null;
+			sessionIds = Collections.singleton(sessionId);
+		}
+		else {
+			sessionIds = getSessionIdsByUser(userName, sessionId);
 		}
-		else if (SimpMessageType.MESSAGE.equals(messageType)) {
-			int prefixEnd = this.prefix.length();
-			int userEnd = destination.indexOf('/', prefixEnd);
-			Assert.isTrue(userEnd > 0, "Expected destination pattern \"/user/{userId}/**\"");
-			String actualDestination = destination.substring(userEnd);
-			String subscribeDestination = this.prefix.substring(0, prefixEnd - 1) + actualDestination;
-			String userName = destination.substring(prefixEnd, userEnd);
-			userName = StringUtils.replace(userName, "%2F", "/");
-			Set<String> sessionIds;
-			if (userName.equals(sessionId)) {
-				userName = null;
+		if (!this.keepLeadingSlash) {
+			actualDestination = actualDestination.substring(1);
+		}
+		return new ParseResult(sourceDestination, actualDestination, subscribeDestination, sessionIds, userName);
+	}
+
+	private Set<String> getSessionIdsByUser(String userName, String sessionId) {
+		Set<String> sessionIds;
+		SimpUser user = this.userRegistry.getUser(userName);
+		if (user != null) {
+			if (user.getSession(sessionId) != null) {
 				sessionIds = Collections.singleton(sessionId);
 			}
 			else {
-				SimpUser user = this.userRegistry.getUser(userName);
-				if (user != null) {
-					if (user.getSession(sessionId) != null) {
-						sessionIds = Collections.singleton(sessionId);
-					}
-					else {
-						Set<SimpSession> sessions = user.getSessions();
-						sessionIds = new HashSet<>(sessions.size());
-						for (SimpSession session : sessions) {
-							sessionIds.add(session.getId());
-						}
-					}
+				Set<SimpSession> sessions = user.getSessions();
+				sessionIds = new HashSet<>(sessions.size());
+				for (SimpSession session : sessions) {
+					sessionIds.add(session.getId());
 				}
-				else {
-					sessionIds = Collections.emptySet();
-				}
-			}
-			if (!this.keepLeadingSlash) {
-				actualDestination = actualDestination.substring(1);
 			}
-			return new ParseResult(actualDestination, subscribeDestination, sessionIds, userName);
 		}
 		else {
-			return null;
+			sessionIds = Collections.emptySet();
 		}
+		return sessionIds;
 	}
 
 	protected boolean checkDestination(String destination, String requiredPrefix) {
@@ -243,8 +259,11 @@ public class DefaultUserDestinationResolver implements UserDestinationResolver {
 
 		private final String user;
 
+		private final String sourceDestination;
 
-		public ParseResult(String actualDest, String subscribeDest, Set<String> sessionIds, String user) {
+		public ParseResult(String sourceDest, String actualDest, String subscribeDest,
+				Set<String> sessionIds, String user) {
+			this.sourceDestination = sourceDest;
 			this.actualDestination = actualDest;
 			this.subscribeDestination = subscribeDest;
 			this.sessionIds = sessionIds;
@@ -267,6 +286,10 @@ public class DefaultUserDestinationResolver implements UserDestinationResolver {
 		public String getUser() {
 			return this.user;
 		}
+
+		public String getSourceDestination() {
+			return this.sourceDestination;
+		}
 	}
 
 }