From bc129e3ad9c9823db73c7c4ade4ca55131b0a5b7 Mon Sep 17 00:00:00 2001
From: md_5 <git@md-5.net>
Date: Fri, 20 Feb 2015 21:39:31 +1100
Subject: [PATCH] Allow Capping (Tile)Entity Tick Time.

This patch adds world configuration options for max-tick-time.entity / max-tick-time.tile which allows setting a hard cap on the amount of time (in milliseconds) that a tick can consume. The default values of 50ms each are very conservative and mean this feature will not activate until the server is well below 15tps (minimum). Values of 20ms each have been reported to provide a good performance increase, however I personally think 25ms for entities and 10-15ms for tiles would give even more significant gains, assuming that these things are not a large priority on your server.

For tiles there is very little tradeoff for this option, as tile ticks are based on wall time for most things, however for entities setting this option too low could lead to jerkiness / lag. The gain however is a faster and more responsive server to other actions such as blocks, chat, combat etc.

This feature was commisioned by Chunkr.

diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index ba5f1db..3c89c0d 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -134,6 +134,9 @@ public abstract class World implements IBlockAccess {
     private final byte chunkTickRadius;
     public static boolean haveWeSilencedAPhysicsCrash;
     public static String blockLocation;
+    private org.spigotmc.TickLimiter entityLimiter;
+    private org.spigotmc.TickLimiter tileLimiter;
+    private int tileTickPosition;
 
     public static long chunkToKey(int x, int z)
     {
@@ -222,6 +225,8 @@ public abstract class World implements IBlockAccess {
         this.getServer().addWorld(this.world); 
         // CraftBukkit end
         timings = new SpigotTimings.WorldTimingsHandler(this); // Spigot - code below can generate new world and access timings 
+        this.entityLimiter = new org.spigotmc.TickLimiter(spigotConfig.entityMaxTickTime);
+        this.tileLimiter = new org.spigotmc.TickLimiter(spigotConfig.tileMaxTickTime);
     }
 
     public World b() {
@@ -1393,7 +1398,12 @@ public abstract class World implements IBlockAccess {
         timings.entityTick.startTiming(); // Spigot
         guardEntityList = true; // Spigot
         // CraftBukkit start - Use field for loop variable
-        for (this.tickPosition = 0; this.tickPosition < this.entityList.size(); ++this.tickPosition) {
+        int entitiesThisCycle = 0;
+        if (tickPosition < 0) tickPosition = 0;
+        for (entityLimiter.initTick();
+                entitiesThisCycle < entityList.size() && (entitiesThisCycle % 10 == 0 || entityLimiter.shouldContinue());
+                tickPosition++, entitiesThisCycle++) {
+            tickPosition = (tickPosition < entityList.size()) ? tickPosition : 0;
             entity = (Entity) this.entityList.get(this.tickPosition);
             // CraftBukkit end
             if (entity.vehicle != null) {
@@ -1449,14 +1459,18 @@ public abstract class World implements IBlockAccess {
             this.c.clear();
         }
         // CraftBukkit end
-        Iterator iterator = this.tileEntityList.iterator();
 
-        while (iterator.hasNext()) {
-            TileEntity tileentity = (TileEntity) iterator.next();
+        // Spigot start
+        int tilesThisCycle = 0;
+        for (tileLimiter.initTick();
+                tilesThisCycle < tileEntityList.size() && (tilesThisCycle % 10 == 0 || tileLimiter.shouldContinue());
+                tileTickPosition++, tilesThisCycle++) {
+            tileTickPosition = (tileTickPosition < tileEntityList.size()) ? tileTickPosition : 0;
+            TileEntity tileentity = (TileEntity) this.tileEntityList.get(tileTickPosition);
             // Spigot start
             if (tileentity == null) {
                 getServer().getLogger().severe("Spigot has detected a null entity and has removed it, preventing a crash");
-                iterator.remove();
+                this.tileEntityList.remove(tileTickPosition--);
                 continue;
             }
             // Spigot end
@@ -1484,7 +1498,7 @@ public abstract class World implements IBlockAccess {
             }
 
             if (tileentity.x()) {
-                iterator.remove();
+                this.tileEntityList.remove(tileTickPosition--);
                 this.h.remove(tileentity);
                 if (this.isLoaded(tileentity.getPosition())) {
                     this.getChunkAtWorldCoords(tileentity.getPosition()).e(tileentity.getPosition());
diff --git a/src/main/java/org/spigotmc/SpigotWorldConfig.java b/src/main/java/org/spigotmc/SpigotWorldConfig.java
index 042ec2a..328ff14 100644
--- a/src/main/java/org/spigotmc/SpigotWorldConfig.java
+++ b/src/main/java/org/spigotmc/SpigotWorldConfig.java
@@ -330,4 +330,13 @@ public class SpigotWorldConfig
     {
         hangingTickFrequency = getInt( "hanging-tick-frequency", 100 );
     }
+
+    public int tileMaxTickTime;
+    public int entityMaxTickTime;
+    private void maxTickTimes()
+    {
+        tileMaxTickTime = getInt("max-tick-time.tile", 50);
+        entityMaxTickTime = getInt("max-tick-time.entity", 50);
+        log("Tile Max Tick Time: " + tileMaxTickTime + "ms Entity max Tick Time: " + entityMaxTickTime + "ms");
+    }
 }
diff --git a/src/main/java/org/spigotmc/TickLimiter.java b/src/main/java/org/spigotmc/TickLimiter.java
new file mode 100644
index 0000000..23a3938
--- /dev/null
+++ b/src/main/java/org/spigotmc/TickLimiter.java
@@ -0,0 +1,20 @@
+package org.spigotmc;
+
+public class TickLimiter {
+
+    private final int maxTime;
+    private long startTime;
+
+    public TickLimiter(int maxtime) {
+        this.maxTime = maxtime;
+    }
+
+    public void initTick() {
+        startTime = System.currentTimeMillis();
+    }
+
+    public boolean shouldContinue() {
+        long remaining = System.currentTimeMillis() - startTime;
+        return remaining < maxTime;
+    }
+}
-- 
2.1.0