Copy dispatcher root children before passing it into async tree building

patches/server/Async-command-map-building.patch

@@ -17,7 +17,9 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
          // CraftBukkit start
          // Register Vanilla commands into builtRoot as before
 +        // Paper start - Perf: Async command map building
-+        COMMAND_SENDING_POOL.execute(() -> this.sendAsync(player));
++        // Copy root children to avoid concurrent modification during building
++        final Collection<CommandNode<CommandSourceStack>> commandNodes = new java.util.ArrayList<>(this.dispatcher.getRoot().getChildren());
++        COMMAND_SENDING_POOL.execute(() -> this.sendAsync(player, commandNodes));
 +    }
 +
 +    public static final java.util.concurrent.ExecutorService COMMAND_SENDING_POOL = java.util.concurrent.Executors.newFixedThreadPool(2,
@@ -27,12 +29,19 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 +            .build()
 +    );
 +
-+    private void sendAsync(ServerPlayer player) {
++    private void sendAsync(ServerPlayer player, Collection<CommandNode<CommandSourceStack>> dispatcherRootChildren) {
 +        // Paper end - Perf: Async command map building
          Map<CommandNode<CommandSourceStack>, CommandNode<SharedSuggestionProvider>> map = Maps.newIdentityHashMap(); // Use identity to prevent aliasing issues
          RootCommandNode vanillaRoot = new RootCommandNode();
  
 @@ -0,0 +0,0 @@ public class Commands {
+         RootCommandNode<SharedSuggestionProvider> rootcommandnode = new RootCommandNode();
+ 
+         map.put(this.dispatcher.getRoot(), rootcommandnode);
+-        this.fillUsableCommands(this.dispatcher.getRoot(), rootcommandnode, player.createCommandSourceStack(), map);
++        this.fillUsableCommands(dispatcherRootChildren, rootcommandnode, player.createCommandSourceStack(), map); // Paper - Perf: Async command map building; pass copy of children
+ 
+         Collection<String> bukkit = new LinkedHashSet<>();
          for (CommandNode node : rootcommandnode.getChildren()) {
              bukkit.add(node.getName());
          }
@@ -47,6 +56,28 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
          PlayerCommandSendEvent event = new PlayerCommandSendEvent(player.getBukkitEntity(), new LinkedHashSet<>(bukkit));
          event.getPlayer().getServer().getPluginManager().callEvent(event);
  
+@@ -0,0 +0,0 @@ public class Commands {
+         player.connection.send(new ClientboundCommandsPacket(rootcommandnode));
+     }
+ 
+-    private void fillUsableCommands(CommandNode<CommandSourceStack> tree, CommandNode<SharedSuggestionProvider> result, CommandSourceStack source, Map<CommandNode<CommandSourceStack>, CommandNode<SharedSuggestionProvider>> resultNodes) {
+-        Iterator iterator = tree.getChildren().iterator();
++    // Paper start - Perf: Async command map building; pass copy of children
++    private void fillUsableCommands(Collection<CommandNode<CommandSourceStack>> children, CommandNode<SharedSuggestionProvider> result, CommandSourceStack source, Map<CommandNode<CommandSourceStack>, CommandNode<SharedSuggestionProvider>> resultNodes) {
++        Iterator iterator = children.iterator();
++        // Paper end - Perf: Async command map building
+ 
+         while (iterator.hasNext()) {
+             CommandNode<CommandSourceStack> commandnode2 = (CommandNode) iterator.next();
+@@ -0,0 +0,0 @@ public class Commands {
+                 resultNodes.put(commandnode2, commandnode3);
+                 result.addChild(commandnode3);
+                 if (!commandnode2.getChildren().isEmpty()) {
+-                    this.fillUsableCommands(commandnode2, commandnode3, source, resultNodes);
++                    this.fillUsableCommands(commandnode2.getChildren(), commandnode3, source, resultNodes); // Paper - Perf: Async command map building; pass children directly
+                 }
+             }
+         }
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
 index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java

patches/server/Brigadier-based-command-API.patch

@@ -2136,7 +2136,7 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
  
                  for (int i = 0; i < Math.min(astacktraceelement.length, 3); ++i) {
 @@ -0,0 +0,0 @@ public class Commands {
-     private void sendAsync(ServerPlayer player) {
+     private void sendAsync(ServerPlayer player, Collection<CommandNode<CommandSourceStack>> dispatcherRootChildren) {
          // Paper end - Perf: Async command map building
          Map<CommandNode<CommandSourceStack>, CommandNode<SharedSuggestionProvider>> map = Maps.newIdentityHashMap(); // Use identity to prevent aliasing issues
 -        RootCommandNode vanillaRoot = new RootCommandNode();
@@ -2151,13 +2151,13 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
  
          map.put(this.dispatcher.getRoot(), rootcommandnode);
 @@ -0,0 +0,0 @@ public class Commands {
-     }
  
-     private void fillUsableCommands(CommandNode<CommandSourceStack> tree, CommandNode<SharedSuggestionProvider> result, CommandSourceStack source, Map<CommandNode<CommandSourceStack>, CommandNode<SharedSuggestionProvider>> resultNodes) {
+     // Paper start - Perf: Async command map building; pass copy of children
+     private void fillUsableCommands(Collection<CommandNode<CommandSourceStack>> children, CommandNode<SharedSuggestionProvider> result, CommandSourceStack source, Map<CommandNode<CommandSourceStack>, CommandNode<SharedSuggestionProvider>> resultNodes) {
 +        resultNodes.keySet().removeIf((node) -> !org.spigotmc.SpigotConfig.sendNamespaced && node.getName().contains( ":" )); // Paper - Remove namedspaced from result nodes to prevent redirect trimming ~ see comment below
-         Iterator iterator = tree.getChildren().iterator();
+         Iterator iterator = children.iterator();
+         // Paper end - Perf: Async command map building
  
-         while (iterator.hasNext()) {
 @@ -0,0 +0,0 @@ public class Commands {
  
              if (commandnode2.canUse(source)) {

patches/server/Fix-entity-type-tags-suggestions-in-selectors.patch

@@ -41,8 +41,8 @@ index 0000000000000000000000000000000000000000..00000000000000000000000000000000
 --- a/src/main/java/net/minecraft/commands/Commands.java
 +++ b/src/main/java/net/minecraft/commands/Commands.java
 @@ -0,0 +0,0 @@ public class Commands {
-         resultNodes.keySet().removeIf((node) -> !org.spigotmc.SpigotConfig.sendNamespaced && node.getName().contains( ":" )); // Paper - Remove namedspaced from result nodes to prevent redirect trimming ~ see comment below
+         Iterator iterator = children.iterator();
-         Iterator iterator = tree.getChildren().iterator();
+         // Paper end - Perf: Async command map building
  
 +        boolean registeredAskServerSuggestionsForTree = false; // Paper - tell clients to ask server for suggestions for EntityArguments
          while (iterator.hasNext()) {