From 4830d3a842271640549c52dd4b70401a26f4e405 Mon Sep 17 00:00:00 2001
From: Sotr <i@omc.hk>
Date: Sat, 9 Jun 2018 00:30:36 +0800
Subject: [PATCH] [Major] Ensures no concurrent tick one world

---
 .../java/io/akarin/server/core/AkarinSlackScheduler.java | 3 ---
 .../akarin/server/mixin/core/MixinMinecraftServer.java   | 9 +++++++--
 2 files changed, 7 insertions(+), 5 deletions(-)

diff --git a/sources/src/main/java/io/akarin/server/core/AkarinSlackScheduler.java b/sources/src/main/java/io/akarin/server/core/AkarinSlackScheduler.java
index 5c96c729b..f5813264e 100644
--- a/sources/src/main/java/io/akarin/server/core/AkarinSlackScheduler.java
+++ b/sources/src/main/java/io/akarin/server/core/AkarinSlackScheduler.java
@@ -1,9 +1,6 @@
 package io.akarin.server.core;
 
-import org.bukkit.entity.Player;
-
 import io.akarin.api.Akari;
-import net.minecraft.server.ChatMessage;
 import net.minecraft.server.EntityPlayer;
 import net.minecraft.server.MinecraftServer;
 import net.minecraft.server.PacketPlayOutKeepAlive;
diff --git a/sources/src/main/java/io/akarin/server/mixin/core/MixinMinecraftServer.java b/sources/src/main/java/io/akarin/server/mixin/core/MixinMinecraftServer.java
index 3026eb462..d203248f1 100644
--- a/sources/src/main/java/io/akarin/server/mixin/core/MixinMinecraftServer.java
+++ b/sources/src/main/java/io/akarin/server/mixin/core/MixinMinecraftServer.java
@@ -140,15 +140,20 @@ public class MixinMinecraftServer {
         Akari.silentTiming = true; // Disable timings
         Akari.STAGE_TICK.submit(() -> {
             // Never tick one world concurrently!
+            // TODO better treat world index
             for (int i = 1; i <= worlds.size(); ++i) {
                 WorldServer world = worlds.get(i < worlds.size() ? i : 0);
-                tickEntities(world);
+                synchronized (world.tickLock) {
+                    tickEntities(world);
+                }
             }
         }, null);
         
         for (int i = 0; i < worlds.size(); ++i) {
             WorldServer world = worlds.get(i);
-            tickWorld(world);
+            synchronized (world.tickLock) {
+                tickWorld(world);
+            }
         }
         
         Akari.STAGE_TICK.take();