From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Callahan <mr.callahhh@gmail.com>
Date: Wed, 8 Apr 2020 02:42:14 -0500
Subject: [PATCH] Async command map building

This adds a custom pool inorder to make sure that they are closed
without much though, as it doesn't matter if the client is not sent
commands if the server is restarting. Using the default async pool caused issues to arise
due to the shutdown logic generally being much later.

diff --git a/src/main/java/net/minecraft/commands/Commands.java b/src/main/java/net/minecraft/commands/Commands.java
index e3394864e29357fec036f9e616472aeab95d035e..b7f1569c662df13f278fc704cabec0400ba7c382 100644
--- a/src/main/java/net/minecraft/commands/Commands.java
+++ b/src/main/java/net/minecraft/commands/Commands.java
@@ -398,6 +398,24 @@ public class Commands {
         if ( org.spigotmc.SpigotConfig.tabComplete < 0 ) return; // Spigot
         // CraftBukkit start
         // Register Vanilla commands into builtRoot as before
+        // Paper start - Async command map building
+        COMMAND_SENDING_POOL.execute(() -> {
+                this.sendAsync(player);
+        });
+    }
+
+    public static final java.util.concurrent.ThreadPoolExecutor COMMAND_SENDING_POOL = new java.util.concurrent.ThreadPoolExecutor(
+        0, 2, 60L, java.util.concurrent.TimeUnit.SECONDS,
+        new java.util.concurrent.LinkedBlockingQueue<>(),
+        new com.google.common.util.concurrent.ThreadFactoryBuilder()
+            .setNameFormat("Paper Async Command Builder Thread Pool - %1$d")
+            .setUncaughtExceptionHandler(new net.minecraft.DefaultUncaughtExceptionHandlerWithName(net.minecraft.server.MinecraftServer.LOGGER))
+            .build(),
+        new java.util.concurrent.ThreadPoolExecutor.DiscardPolicy()
+    );
+
+    private void sendAsync(ServerPlayer player) {
+        // Paper end - Async command map building
         Map<CommandNode<CommandSourceStack>, CommandNode<SharedSuggestionProvider>> map = Maps.newIdentityHashMap(); // Use identity to prevent aliasing issues
         RootCommandNode vanillaRoot = new RootCommandNode();
 
@@ -415,7 +433,14 @@ public class Commands {
         for (CommandNode node : rootcommandnode.getChildren()) {
             bukkit.add(node.getName());
         }
+        // Paper start - Async command map building
+        net.minecraft.server.MinecraftServer.getServer().execute(() -> {
+           runSync(player, bukkit, rootcommandnode);
+        });
+    }
 
+    private void runSync(ServerPlayer player, Collection<String> bukkit, RootCommandNode<SharedSuggestionProvider> rootcommandnode) {
+        // Paper end - Async command map building
         PlayerCommandSendEvent event = new PlayerCommandSendEvent(player.getBukkitEntity(), new LinkedHashSet<>(bukkit));
         event.getPlayer().getServer().getPluginManager().callEvent(event);
 
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index b6535f3a4d1e7c3d009d14b151fc06c8811678bd..b29d5da64bfb05455abb4b012d17e4113b5b6f12 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -898,6 +898,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
         }
 
         MinecraftServer.LOGGER.info("Stopping server");
+        Commands.COMMAND_SENDING_POOL.shutdownNow(); // Paper - Shutdown and don't bother finishing
         MinecraftTimings.stopServer(); // Paper
         // CraftBukkit start
         if (this.server != null) {