Force commands to be dispatched synchronously

[22:29:12] <Aikar> just add that
[22:29:17] <Aikar> that forces it fixed
[22:29:31] <Aikar> and then when his users spam him hell fix it :P

Spigot-Server-Patches/0083-Ensure-commands-are-not-ran-async.patch

@@ -0,0 +1,86 @@
+From 3d5bf73817dbd5e89595cc27a80a9cfe0b5860eb Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Wed, 8 Oct 2014 19:51:28 -0400
+Subject: [PATCH] Ensure commands are not ran async
+
+Plugins calling Player.chat("/foo") or Server.dispatchCommand() could
+trigger the server to execute a command while on another thread.
+
+These commands would then process EXPECTING to be on the main thread, leaving to
+very hard to trace concurrency issues.
+
+This change will synchronize the command execution back to the main thread, causing a
+big slowdown in execution but throwing an exception at same time to raise awareness
+that it is happening so that plugin authors can fix their code to stop executing commands async.
+
+diff --git a/src/main/java/net/minecraft/server/PlayerConnection.java b/src/main/java/net/minecraft/server/PlayerConnection.java
+index 1138042..4391ad7 100644
+--- a/src/main/java/net/minecraft/server/PlayerConnection.java
++++ b/src/main/java/net/minecraft/server/PlayerConnection.java
+@@ -1079,6 +1079,29 @@ public class PlayerConnection implements PacketListenerPlayIn, IUpdatePlayerList
+         }
+ 
+         if (!async && s.startsWith("/")) {
++            // PaperSpigot Start
++            if (!org.bukkit.Bukkit.isPrimaryThread()) {
++                final String fCommandLine = s;
++                MinecraftServer.LOGGER.log(org.apache.logging.log4j.Level.ERROR, "Command Dispatched Async: " + fCommandLine);
++                MinecraftServer.LOGGER.log(org.apache.logging.log4j.Level.ERROR, "Please notify author of plugin causing this execution to fix this bug! see: http://bit.ly/1oSiM6C", new Throwable());
++                Waitable wait = new Waitable() {
++                    @Override
++                    protected Object evaluate() {
++                        chat(fCommandLine, false);
++                        return null;
++                    }
++                };
++                minecraftServer.processQueue.add(wait);
++                try {
++                    wait.get();
++                    return;
++                } catch (InterruptedException e) {
++                    Thread.currentThread().interrupt(); // This is proper habit for java. If we aren't handling it, pass it on!
++                } catch (Exception e) {
++                    throw new RuntimeException("Exception processing chat command", e.getCause());
++                }
++            }
++            // PaperSpigot End
+             this.handleCommand(s);
+         } else if (this.player.getChatFlags() == EntityHuman.EnumChatVisibility.SYSTEM) {
+             // Do nothing, this is coming from a plugin
+diff --git a/src/main/java/org/bukkit/craftbukkit/CraftServer.java b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+index 97f9f96..a54b3e8 100644
+--- a/src/main/java/org/bukkit/craftbukkit/CraftServer.java
++++ b/src/main/java/org/bukkit/craftbukkit/CraftServer.java
+@@ -639,6 +639,29 @@ public final class CraftServer implements Server {
+         Validate.notNull(sender, "Sender cannot be null");
+         Validate.notNull(commandLine, "CommandLine cannot be null");
+ 
++        // PaperSpigot Start
++        if (!Bukkit.isPrimaryThread()) {
++            final CommandSender fSender = sender;
++            final String fCommandLine = commandLine;
++            Bukkit.getLogger().log(Level.SEVERE, "Command Dispatched Async: " + commandLine);
++            Bukkit.getLogger().log(Level.SEVERE, "Please notify author of plugin causing this execution to fix this bug! see: http://bit.ly/1oSiM6C", new Throwable());
++            org.bukkit.craftbukkit.util.Waitable<Boolean> wait = new org.bukkit.craftbukkit.util.Waitable<Boolean>() {
++                @Override
++                protected Boolean evaluate() {
++                    return dispatchCommand(fSender, fCommandLine);
++                }
++            };
++            net.minecraft.server.MinecraftServer.getServer().processQueue.add(wait);
++            try {
++                return wait.get();
++            } catch (InterruptedException e) {
++                Thread.currentThread().interrupt(); // This is proper habit for java. If we aren't handling it, pass it on!
++            } catch (Exception e) {
++                throw new RuntimeException("Exception processing dispatch command", e.getCause());
++            }
++        }
++        // PaperSpigot End
++
+         if (commandMap.dispatch(sender, commandLine)) {
+             return true;
+         }
+-- 
+2.7.0
+