Fix some concurrency issues with login handling

common/src/main/java/me/lucko/luckperms/common/constants/Message.java

@@ -27,6 +27,7 @@ import lombok.Getter;
 
 import me.lucko.luckperms.common.commands.sender.Sender;
 import me.lucko.luckperms.common.commands.utils.Util;
+import me.lucko.luckperms.common.locale.LocaleManager;
 
 @SuppressWarnings("SpellCheckingInspection")
 @AllArgsConstructor
@@ -44,7 +45,7 @@ public enum Message {
     EMPTY("{0}", true),
     PLAYER_ONLINE("&aOnline", false),
     PLAYER_OFFLINE("&cOffline", false),
-    LOADING_ERROR("Permissions data could not be loaded. Please contact an administrator.", true),
+    LOADING_ERROR("Permissions data could not be loaded. Please try again later.", true),
     OP_DISABLED("&bThe vanilla OP system is disabled on this server.", false),
     OP_DISABLED_SPONGE("&2Server Operator status has no effect when a permission plugin is installed. Please edit user data directly.", true),
     LOG("&3LOG &3&l> {0}", true),
@@ -452,6 +453,21 @@ public enum Message {
         return Util.color(showPrefix ? PREFIX + message : message);
     }
 
+    public String asString(LocaleManager localeManager) {
+        String prefix = localeManager.getTranslation(PREFIX);
+        if (prefix == null) {
+            prefix = PREFIX.getMessage();
+        }
+
+        String s = localeManager.getTranslation(this);
+        if (s == null) {
+            s = message;
+        }
+
+        s = s.replace("{PREFIX}", prefix).replace("\\n", "\n");
+        return Util.color(showPrefix ? (prefix + s) : (s));
+    }
+
     public void send(Sender sender, Object... objects) {
         String prefix = sender.getPlatform().getLocaleManager().getTranslation(PREFIX);
         if (prefix == null) {

common/src/main/java/me/lucko/luckperms/common/managers/UserManager.java

@@ -60,6 +60,13 @@ public interface UserManager extends Manager<UserIdentifier, User> {
      */
     void cleanup(User user);
 
+    /**
+     * Schedules a task to cleanup a user after a certain period of time, if they're not on the server anymore.
+     *
+     * @param uuid external uuid of the player
+     */
+    void scheduleUnload(UUID uuid);
+
     /**
      * Reloads the data of all online users
      */

common/src/main/java/me/lucko/luckperms/common/managers/impl/GenericUserManager.java

@@ -134,6 +134,18 @@ public class GenericUserManager extends AbstractManager<UserIdentifier, User> im
         }
     }
 
+    @Override
+    public void scheduleUnload(UUID uuid) {
+        plugin.getScheduler().doAsyncLater(() -> {
+            User user = get(plugin.getUuidCache().getUUID(uuid));
+            if (user != null && !plugin.isPlayerOnline(uuid)) {
+                user.unregisterData();
+                unload(user);
+            }
+            plugin.getUuidCache().clearCache(uuid);
+        }, 40L);
+    }
+
     @Override
     public void updateAllUsers() {
         plugin.doSync(() -> {

common/src/main/java/me/lucko/luckperms/common/utils/LoginHelper.java

@@ -22,7 +22,7 @@
 
 package me.lucko.luckperms.common.utils;
 
-import lombok.AllArgsConstructor;
+import lombok.experimental.UtilityClass;
 
 import me.lucko.luckperms.common.config.ConfigKeys;
 import me.lucko.luckperms.common.core.UuidCache;
@@ -33,13 +33,12 @@ import me.lucko.luckperms.common.plugin.LuckPermsPlugin;
 import java.util.UUID;
 
 /**
- * An abstract listener shared by Bukkit & Sponge.
+ * Utilities for use in platform listeners
  */
-@AllArgsConstructor
-public class AbstractListener {
-    private final LuckPermsPlugin plugin;
+@UtilityClass
+public class LoginHelper {
 
-    public void onAsyncLogin(UUID u, String username) {
+    public static void loadUser(LuckPermsPlugin plugin, UUID u, String username) {
         final long startTime = System.currentTimeMillis();
 
         final UuidCache cache = plugin.getUuidCache();
@@ -67,6 +66,7 @@ public class AbstractListener {
         User user = plugin.getUserManager().get(cache.getUUID(u));
         if (user == null) {
             plugin.getLog().warn("Failed to load user: " + username);
+            throw new RuntimeException("Failed to load user");
         } else {
             // Setup defaults for the user
             boolean save = false;
@@ -90,20 +90,7 @@ public class AbstractListener {
         }
     }
 
-    protected void onLeave(UUID uuid) {
-        final UuidCache cache = plugin.getUuidCache();
-
-        final User user = plugin.getUserManager().get(cache.getUUID(uuid));
-        if (user != null) {
-            user.unregisterData();
-            plugin.getUserManager().unload(user);
-        }
-
-        // Unload the user from memory when they disconnect;
-        cache.clearCache(uuid);
-    }
-
-    protected void refreshPlayer(UUID uuid) {
+    public static void refreshPlayer(LuckPermsPlugin plugin, UUID uuid) {
         final User user = plugin.getUserManager().get(plugin.getUuidCache().getUUID(uuid));
         if (user != null) {
             user.getRefreshBuffer().requestDirectly();