Implement allocation-friendly method to get user count in SimpUserRegistry

SPR-14930
(cherry picked from commit a929e9c)

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

@@ -135,6 +135,16 @@ public class MultiServerUserRegistry implements SimpUserRegistry, SmartApplicati
 		return result;
 	}
 
+	@Override
+	public int getUserCount() {
+		int userCount = 0;
+		for (UserRegistrySnapshot registry : this.remoteRegistries.values()) {
+			userCount += registry.getUserMap().size();
+		}
+		userCount += this.localRegistry.getUserCount();
+		return userCount;
+	}
+
 	@Override
 	public Set<SimpSubscription> findSubscriptions(SimpSubscriptionMatcher matcher) {
 		Set<SimpSubscription> result = new HashSet<SimpSubscription>();

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

@@ -1,5 +1,5 @@
 /*
- * Copyright 2002-2015 the original author or authors.
+ * Copyright 2002-2016 the original author or authors.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,21 +29,28 @@ public interface SimpUserRegistry {
 	/**
 	 * Get the user for the given name.
 	 * @param userName the name of the user to look up
-	 * @return the user or {@code null} if not connected
+	 * @return the user, or {@code null} if not connected
 	 */
 	SimpUser getUser(String userName);
 
 	/**
-	 * Return a snapshot of all connected users. The returned set is a copy and
-	 * will never be modified.
-	 * @return the connected users or an empty set.
+	 * Return a snapshot of all connected users.
+	 * <p>The returned set is a copy and will not reflect further changes.
+	 * @return the connected users, or an empty set if none
 	 */
 	Set<SimpUser> getUsers();
 
+	/**
+	 * Return the count of all connected users.
+	 * @return the number of connected users
+	 * @since 4.3.5
+	 */
+	int getUserCount();
+
 	/**
 	 * Find subscriptions with the given matcher.
 	 * @param matcher the matcher to use
-	 * @return a set of matching subscriptions or an empty set.
+	 * @return a set of matching subscriptions, or an empty set if none
 	 */
 	Set<SimpSubscription> findSubscriptions(SimpSubscriptionMatcher matcher);
 

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

@@ -59,6 +59,11 @@ public class UserSessionRegistryAdapter implements SimpUserRegistry {
 		throw new UnsupportedOperationException("UserSessionRegistry does not expose a listing of users");
 	}
 
+	@Override
+	public int getUserCount() {
+		throw new UnsupportedOperationException("UserSessionRegistry does not expose a user count");
+	}
+
 	@Override
 	public Set<SimpSubscription> findSubscriptions(SimpSubscriptionMatcher matcher) {
 		throw new UnsupportedOperationException("UserSessionRegistry does not support operations across users");

spring-messaging/src/test/java/org/springframework/messaging/simp/user/MultiServerUserRegistryTests.java

@@ -61,9 +61,10 @@ public class MultiServerUserRegistryTests {
 		SimpUser user = Mockito.mock(SimpUser.class);
 		Set<SimpUser> users = Collections.singleton(user);
 		when(this.localRegistry.getUsers()).thenReturn(users);
+		when(this.localRegistry.getUserCount()).thenReturn(1);
 		when(this.localRegistry.getUser("joe")).thenReturn(user);
 
-		assertEquals(1, this.registry.getUsers().size());
+		assertEquals(1, this.registry.getUserCount());
 		assertSame(user, this.registry.getUser("joe"));
 	}
 
@@ -84,7 +85,7 @@ public class MultiServerUserRegistryTests {
 		this.registry.addRemoteRegistryDto(message, this.converter, 20000);
 
 
-		assertEquals(1, this.registry.getUsers().size());
+		assertEquals(1, this.registry.getUserCount());
 		SimpUser user = this.registry.getUser("joe");
 		assertNotNull(user);
 		assertTrue(user.hasSessions());
@@ -125,7 +126,7 @@ public class MultiServerUserRegistryTests {
 		this.registry.addRemoteRegistryDto(message, this.converter, 20000);
 
 
-		assertEquals(3, this.registry.getUsers().size());
+		assertEquals(3, this.registry.getUserCount());
 		Set<SimpSubscription> matches = this.registry.findSubscriptions(s -> s.getDestination().equals("/match"));
 		assertEquals(2, matches.size());
 		Iterator<SimpSubscription> iterator = matches.iterator();
@@ -157,7 +158,7 @@ public class MultiServerUserRegistryTests {
 		this.registry.addRemoteRegistryDto(message, this.converter, 20000);
 
 
-		assertEquals(1, this.registry.getUsers().size());
+		assertEquals(1, this.registry.getUserCount());
 		SimpUser user = this.registry.getUsers().iterator().next();
 		assertTrue(user.hasSessions());
 		assertEquals(2, user.getSessions().size());
@@ -187,9 +188,9 @@ public class MultiServerUserRegistryTests {
 		this.registry.addRemoteRegistryDto(message, this.converter, -1);
 
 
-		assertEquals(1, this.registry.getUsers().size());
+		assertEquals(1, this.registry.getUserCount());
 		this.registry.purgeExpiredRegistries();
-		assertEquals(0, this.registry.getUsers().size());
+		assertEquals(0, this.registry.getUserCount());
 	}
 
 }

spring-messaging/src/test/java/org/springframework/messaging/simp/user/UserRegistryMessageHandlerTests.java

@@ -126,7 +126,7 @@ public class UserRegistryMessageHandlerTests {
 
 		MultiServerUserRegistry remoteRegistry = new MultiServerUserRegistry(mock(SimpUserRegistry.class));
 		remoteRegistry.addRemoteRegistryDto(message, this.converter, 20000);
-		assertEquals(2, remoteRegistry.getUsers().size());
+		assertEquals(2, remoteRegistry.getUserCount());
 		assertNotNull(remoteRegistry.getUser("joe"));
 		assertNotNull(remoteRegistry.getUser("jane"));
 	}
@@ -142,6 +142,7 @@ public class UserRegistryMessageHandlerTests {
 
 		HashSet<SimpUser> simpUsers = new HashSet<>(Arrays.asList(simpUser1, simpUser2));
 		SimpUserRegistry remoteUserRegistry = mock(SimpUserRegistry.class);
+		when(remoteUserRegistry.getUserCount()).thenReturn(2);
 		when(remoteUserRegistry.getUsers()).thenReturn(simpUsers);
 
 		MultiServerUserRegistry remoteRegistry = new MultiServerUserRegistry(remoteUserRegistry);
@@ -149,7 +150,7 @@ public class UserRegistryMessageHandlerTests {
 
 		this.handler.handleMessage(message);
 
-		assertEquals(2, remoteRegistry.getUsers().size());
+		assertEquals(2, remoteRegistry.getUserCount());
 		assertNotNull(this.multiServerRegistry.getUser("joe"));
 		assertNotNull(this.multiServerRegistry.getUser("jane"));
 	}
@@ -159,13 +160,14 @@ public class UserRegistryMessageHandlerTests {
 
 		TestSimpUser simpUser = new TestSimpUser("joe");
 		simpUser.addSessions(new TestSimpSession("123"));
+		when(this.localRegistry.getUserCount()).thenReturn(1);
 		when(this.localRegistry.getUsers()).thenReturn(Collections.singleton(simpUser));
 
-		assertEquals(1, this.multiServerRegistry.getUsers().size());
+		assertEquals(1, this.multiServerRegistry.getUserCount());
 
 		Message<?> message = this.converter.toMessage(this.multiServerRegistry.getLocalRegistryDto(), null);
 		this.multiServerRegistry.addRemoteRegistryDto(message, this.converter, 20000);
-		assertEquals(1, this.multiServerRegistry.getUsers().size());
+		assertEquals(1, this.multiServerRegistry.getUserCount());
 	}
 
 

spring-websocket/src/main/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistry.java

@@ -141,6 +141,11 @@ public class DefaultSimpUserRegistry implements SimpUserRegistry, SmartApplicati
 		return new HashSet<SimpUser>(this.users.values());
 	}
 
+	@Override
+	public int getUserCount() {
+		return this.users.size();
+	}
+
 	public Set<SimpSubscription> findSubscriptions(SimpSubscriptionMatcher matcher) {
 		Set<SimpSubscription> result = new HashSet<SimpSubscription>();
 		for (LocalSimpSession session : this.sessions.values()) {

spring-websocket/src/test/java/org/springframework/web/socket/messaging/DefaultSimpUserRegistryTests.java

@@ -57,6 +57,7 @@ public class DefaultSimpUserRegistryTests {
 		SimpUser simpUser = registry.getUser("joe");
 		assertNotNull(simpUser);
 
+		assertEquals(1, registry.getUserCount());
 		assertEquals(1, simpUser.getSessions().size());
 		assertNotNull(simpUser.getSession("123"));
 	}
@@ -82,6 +83,7 @@ public class DefaultSimpUserRegistryTests {
 		SimpUser simpUser = registry.getUser("joe");
 		assertNotNull(simpUser);
 
+		assertEquals(1, registry.getUserCount());
 		assertEquals(3, simpUser.getSessions().size());
 		assertNotNull(simpUser.getSession("123"));
 		assertNotNull(simpUser.getSession("456"));