From 23dac3287b50f36273820f0d81a38c5de7ba90c5 Mon Sep 17 00:00:00 2001
From: Pasqual Koschmieder <pasqual.koschmieder@gmail.com>
Date: Sat, 16 Jul 2022 17:00:01 +0200
Subject: [PATCH] detect server reloads and print a big warning message (#1733)

---
 .../com/comphenix/protocol/ProtocolLib.java   | 14 +++++
 .../com/comphenix/protocol/utility/Util.java  | 51 ++++++++++++-------
 2 files changed, 48 insertions(+), 17 deletions(-)

diff --git a/src/main/java/com/comphenix/protocol/ProtocolLib.java b/src/main/java/com/comphenix/protocol/ProtocolLib.java
index 39909d5d..e2a6b8c1 100644
--- a/src/main/java/com/comphenix/protocol/ProtocolLib.java
+++ b/src/main/java/com/comphenix/protocol/ProtocolLib.java
@@ -32,6 +32,7 @@ import com.comphenix.protocol.utility.ByteBuddyFactory;
 import com.comphenix.protocol.utility.ChatExtensions;
 import com.comphenix.protocol.utility.MinecraftVersion;
 import com.comphenix.protocol.utility.NettyVersion;
+import com.comphenix.protocol.utility.Util;
 import com.google.common.base.Splitter;
 import com.google.common.collect.Iterables;
 import java.io.File;
@@ -569,6 +570,19 @@ public class ProtocolLib extends JavaPlugin {
 			return;
 		}
 
+		// that reloading the server might break ProtocolLib / plugins depending on it
+		if (Util.isCurrentlyReloading()) {
+			logger.severe("╔══════════════════════════════════════════════════════════════════╗");
+			logger.severe("║                               WARNING                            ║");
+			logger.severe("║     RELOADING THE SERVER WHILE PROTOCOL LIB IS ENABLED MIGHT     ║");
+			logger.severe("║                    LEAD TO UNEXPECTED ERRORS!                    ║");
+			logger.severe("║                                                                  ║");
+			logger.severe("║     Consider to cleanly restart your server if you encounter     ║");
+			logger.severe("║    any issues related to Protocol Lib before opening an issue    ║");
+			logger.severe("║                            on GitHub!                            ║");
+			logger.severe("╚══════════════════════════════════════════════════════════════════╝");
+		}
+
 		// Disable compiler
 		if (this.backgroundCompiler != null) {
 			this.backgroundCompiler.shutdownAll();
diff --git a/src/main/java/com/comphenix/protocol/utility/Util.java b/src/main/java/com/comphenix/protocol/utility/Util.java
index 2aa708b7..703d204f 100644
--- a/src/main/java/com/comphenix/protocol/utility/Util.java
+++ b/src/main/java/com/comphenix/protocol/utility/Util.java
@@ -1,18 +1,16 @@
 /**
- *  ProtocolLib - Bukkit server library that allows access to the Minecraft protocol.
- *  Copyright (C) 2015 dmulloy2
- *
- *  This program is free software; you can redistribute it and/or modify it under the terms of the
- *  GNU General Public License as published by the Free Software Foundation; either version 2 of
- *  the License, or (at your option) any later version.
- *
- *  This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY;
- *  without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
- *  See the GNU General Public License for more details.
- *
- *  You should have received a copy of the GNU General Public License along with this program;
- *  if not, write to the Free Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
- *  02111-1307 USA
+ * ProtocolLib - Bukkit server library that allows access to the Minecraft protocol. Copyright (C) 2015 dmulloy2
+ * <p>
+ * This program is free software; you can redistribute it and/or modify it under the terms of the GNU General Public
+ * License as published by the Free Software Foundation; either version 2 of the License, or (at your option) any later
+ * version.
+ * <p>
+ * This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied
+ * warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more
+ * details.
+ * <p>
+ * You should have received a copy of the GNU General Public License along with this program; if not, write to the Free
+ * Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  */
 package com.comphenix.protocol.utility;
 
@@ -26,7 +24,10 @@ import java.util.List;
  */
 public final class Util {
 
-	private Util() {}
+	private static final boolean spigot = classExists("org.spigotmc.SpigotConfig");
+
+	private Util() {
+	}
 
 	/**
 	 * Converts a variable argument array into a List.
@@ -49,8 +50,6 @@ public final class Util {
 		}
 	}
 
-	private static final boolean spigot = classExists("org.spigotmc.SpigotConfig");
-
 	/**
 	 * Whether or not this server is running Spigot or a Spigot fork. This works by checking
 	 * if the SpigotConfig exists, which should be true of all forks.
@@ -59,4 +58,22 @@ public final class Util {
 	public static boolean isUsingSpigot() {
 		return spigot;
 	}
+
+	/**
+	 * Checks if the server is getting reloaded by walking down the current thread stack trace.
+	 *
+	 * @return true if the server is getting reloaded, false otherwise.
+	 */
+	public static boolean isCurrentlyReloading() {
+		StackTraceElement[] stackTrace = Thread.currentThread().getStackTrace();
+		for (StackTraceElement element : stackTrace) {
+			String clazz = element.getClassName();
+			if (clazz.startsWith("org.bukkit.craftbukkit.")
+					&& clazz.endsWith(".CraftServer")
+					&& element.getMethodName().equals("reload")) {
+				return true;
+			}
+		}
+		return false;
+	}
 }