From c512261fb7d8d8d89caab2fc55189d9372cadf4a Mon Sep 17 00:00:00 2001
From: PikaMug <2267126+PikaMug@users.noreply.github.com>
Date: Wed, 4 Nov 2020 16:11:47 -0500
Subject: [PATCH] Address concurrent modification of quester list, fixes #1439

---
 .../java/me/blackvein/quests/Quester.java     | 35 ++++++++++++++-----
 .../main/java/me/blackvein/quests/Quests.java | 17 ++++-----
 2 files changed, 36 insertions(+), 16 deletions(-)

diff --git a/main/src/main/java/me/blackvein/quests/Quester.java b/main/src/main/java/me/blackvein/quests/Quester.java
index 27d0030a2..fe9762f92 100644
--- a/main/src/main/java/me/blackvein/quests/Quester.java
+++ b/main/src/main/java/me/blackvein/quests/Quester.java
@@ -233,6 +233,11 @@ public class Quester {
     public Quester(final Quests plugin) {
         this.plugin = plugin;
     }
+    
+    public Quester(final Quests plugin, final UUID uuid) {
+        this.plugin = plugin;
+        this.id = uuid;
+    }
 
     public UUID getUUID() {
         return id;
@@ -3189,6 +3194,23 @@ public class Quester {
         return data;
     }
 
+    /**
+     * Check whether data file for this Quester exists
+     * 
+     * @return file if exists, otherwise null
+     */
+    public File getDataFile() {
+        File dataFile = new File(plugin.getDataFolder(), "data" + File.separator + id.toString() + ".yml");
+        if (!dataFile.exists()) {
+            final OfflinePlayer p = getOfflinePlayer();
+            dataFile = new File(plugin.getDataFolder(), "data" + File.separator + p.getName() + ".yml");
+            if (!dataFile.exists()) {
+                return null;
+            }
+        }
+        return dataFile;
+    }
+    
     /**
      * Load data of the Quester from file
      * 
@@ -3198,15 +3220,12 @@ public class Quester {
     public boolean loadData() {
         final FileConfiguration data = new YamlConfiguration();
         try {
-            File dataFile = new File(plugin.getDataFolder(), "data" + File.separator + id.toString() + ".yml");
-            if (dataFile.exists() == false) {
-                final OfflinePlayer p = getOfflinePlayer();
-                dataFile = new File(plugin.getDataFolder(), "data" + File.separator + p.getName() + ".yml");
-                if (dataFile.exists() == false) {
-                    return false;
-                }
+            final File dataFile = getDataFile();
+            if (dataFile != null) {
+                data.load(dataFile);
+            } else {
+                return false;
             }
-            data.load(dataFile);
         } catch (final IOException e) {
             return false;
         } catch (final InvalidConfigurationException e) {
diff --git a/main/src/main/java/me/blackvein/quests/Quests.java b/main/src/main/java/me/blackvein/quests/Quests.java
index 87da51d3e..07ebecc05 100644
--- a/main/src/main/java/me/blackvein/quests/Quests.java
+++ b/main/src/main/java/me/blackvein/quests/Quests.java
@@ -1304,22 +1304,24 @@ public class Quests extends JavaPlugin implements ConversationAbandonedListener
         if (id == null) {
             return null;
         }
-        for (final Quester q: questers) {
+        final ConcurrentSkipListSet<Quester> set = (ConcurrentSkipListSet<Quester>) questers;
+        for (final Quester q: set) {
             if (q != null && q.getUUID().equals(id)) {
                 return q;
             }
         }
-        final Quester quester = new Quester(this);
-        quester.setUUID(id);
+        final Quester quester = new Quester(this, id);
         if (depends.getCitizens() != null) {
             if (depends.getCitizens().getNPCRegistry().getByUniqueId(id) != null) {
                 return quester;
             }
         }
-        questers.add(quester);
         if (!quester.loadData()) {
-            questers.remove(quester);
+            set.add(quester);
+        } else {
+            set.remove(quester);
         }
+        setOfflineQuesters(set);
         return quester;
     }
 
@@ -1333,9 +1335,8 @@ public class Quests extends JavaPlugin implements ConversationAbandonedListener
     public LinkedList<Quester> getOnlineQuesters() {
         final LinkedList<Quester> qs = new LinkedList<Quester>();
         for (final Player p : getServer().getOnlinePlayers()) {
-            final Quester quester = new Quester(this);
-            quester.setUUID(p.getUniqueId());
-            if (quester.loadData() == false) {
+            final Quester quester = new Quester(this, p.getUniqueId());
+            if (!quester.loadData()) {
                 quester.saveData();
             }
             qs.add(quester);