From 1cef4400b9dc42b7fd7a8abde66617c82b02308d Mon Sep 17 00:00:00 2001
From: NEZNAMY <n.e.z.n.a.m.y@azet.sk>
Date: Sat, 18 Jan 2025 14:23:13 +0100
Subject: [PATCH] [Scoreboard] Fix ConcurrentModificationException when using
 API (#1410)

---
 .../features/scoreboard/ScoreboardImpl.java   |  6 +++++-
 .../scoreboard/lines/ScoreboardLine.java      | 20 ++++++++++++++-----
 2 files changed, 20 insertions(+), 6 deletions(-)

diff --git a/shared/src/main/java/me/neznamy/tab/shared/features/scoreboard/ScoreboardImpl.java b/shared/src/main/java/me/neznamy/tab/shared/features/scoreboard/ScoreboardImpl.java
index 5bf91b1d8..ba33c2109 100644
--- a/shared/src/main/java/me/neznamy/tab/shared/features/scoreboard/ScoreboardImpl.java
+++ b/shared/src/main/java/me/neznamy/tab/shared/features/scoreboard/ScoreboardImpl.java
@@ -22,6 +22,7 @@
 import org.jetbrains.annotations.Nullable;
 
 import java.util.*;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * A class representing a scoreboard configured in config
@@ -50,7 +51,7 @@ public class ScoreboardImpl extends RefreshableFeature implements me.neznamy.tab
     private boolean containsNumberFormat;
 
     //players currently seeing this scoreboard
-    private final Set<TabPlayer> players = Collections.newSetFromMap(new WeakHashMap<>());
+    private final Set<TabPlayer> players = Collections.newSetFromMap(new ConcurrentHashMap<>());
 
     /**
      * Constructs new instance with given parameters and registers lines to feature manager
@@ -238,6 +239,9 @@ public void recalculateScores(@NonNull TabPlayer p) {
      */
     public void removePlayerFromSet(@NonNull TabPlayer player) {
         players.remove(player);
+        for (Line line : lines) {
+            ((ScoreboardLine)line).removePlayerSilently(player);
+        }
     }
 
     @NotNull
diff --git a/shared/src/main/java/me/neznamy/tab/shared/features/scoreboard/lines/ScoreboardLine.java b/shared/src/main/java/me/neznamy/tab/shared/features/scoreboard/lines/ScoreboardLine.java
index 58b5b2364..fae395f9e 100644
--- a/shared/src/main/java/me/neznamy/tab/shared/features/scoreboard/lines/ScoreboardLine.java
+++ b/shared/src/main/java/me/neznamy/tab/shared/features/scoreboard/lines/ScoreboardLine.java
@@ -2,25 +2,25 @@
 
 import lombok.Getter;
 import lombok.NonNull;
+import me.neznamy.tab.api.scoreboard.Line;
 import me.neznamy.tab.shared.Limitations;
 import me.neznamy.tab.shared.TAB;
 import me.neznamy.tab.shared.TabConstants;
 import me.neznamy.tab.shared.chat.EnumChatFormat;
-import me.neznamy.tab.api.scoreboard.Line;
 import me.neznamy.tab.shared.chat.TextColor;
 import me.neznamy.tab.shared.cpu.ThreadExecutor;
 import me.neznamy.tab.shared.features.scoreboard.ScoreRefresher;
+import me.neznamy.tab.shared.features.scoreboard.ScoreboardImpl;
+import me.neznamy.tab.shared.features.scoreboard.ScoreboardManagerImpl;
 import me.neznamy.tab.shared.features.types.CustomThreaded;
 import me.neznamy.tab.shared.features.types.RefreshableFeature;
 import me.neznamy.tab.shared.platform.Scoreboard;
 import me.neznamy.tab.shared.platform.TabPlayer;
-import me.neznamy.tab.shared.features.scoreboard.ScoreboardImpl;
-import me.neznamy.tab.shared.features.scoreboard.ScoreboardManagerImpl;
 import org.jetbrains.annotations.NotNull;
 
 import java.util.Collections;
 import java.util.Set;
-import java.util.WeakHashMap;
+import java.util.concurrent.ConcurrentHashMap;
 
 /**
  * Abstract class representing a line of scoreboard
@@ -46,7 +46,7 @@ public abstract class ScoreboardLine extends RefreshableFeature implements Line,
 
     private final ScoreRefresher scoreRefresher;
 
-    private final Set<TabPlayer> shownPlayers = Collections.newSetFromMap(new WeakHashMap<>());
+    private final Set<TabPlayer> shownPlayers = Collections.newSetFromMap(new ConcurrentHashMap<>());
     
     /**
      * Constructs new instance with given parameters
@@ -258,6 +258,16 @@ protected void updateTeam(@NotNull TabPlayer player, @NotNull String prefix, @No
         );
     }
 
+    /**
+     * Silently removes players from the list of players this line is shown to.
+     *
+     * @param   player
+     *          Player to remove
+     */
+    public void removePlayerSilently(@NonNull TabPlayer player) {
+        shownPlayers.remove(player);
+    }
+
     @Override
     @NotNull
     public ThreadExecutor getCustomThread() {