From 7316080501bd346405991b9dc4d68c8dfa363267 Mon Sep 17 00:00:00 2001
From: md_5 <git@md-5.net>
Date: Thu, 26 Jan 2017 21:50:51 +0000
Subject: [PATCH] Highly Optimized Tick Loop


diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index 7aa788871..540079fcb 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -147,6 +147,12 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
     public File bukkitDataPackFolder;
     public CommandDispatcher vanillaCommandDispatcher;
     // CraftBukkit end
+    // Spigot start
+    public static final int TPS = 20;
+    public static final int TICK_TIME = 1000000000 / TPS;
+    private static final int SAMPLE_INTERVAL = 100;
+    public final double[] recentTps = new double[ 3 ];
+    // Spigot end
 
     public MinecraftServer(OptionSet options, Proxy proxy, DataFixer datafixer, CommandDispatcher commanddispatcher, YggdrasilAuthenticationService yggdrasilauthenticationservice, MinecraftSessionService minecraftsessionservice, GameProfileRepository gameprofilerepository, UserCache usercache) {
         this.ac = new ResourceManager(EnumResourcePackType.SERVER_DATA);
@@ -660,6 +666,13 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
         this.isRunning = false;
     }
 
+    // Spigot Start
+    private static double calcTps(double avg, double exp, double tps)
+    {
+        return ( avg * exp ) + ( tps * ( 1 - exp ) );
+    }
+    // Spigot End
+
     public void run() {
         try {
             if (this.init()) {
@@ -668,28 +681,36 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
                 this.n.setServerInfo(new ServerPing.ServerData("1.13", 393));
                 this.a(this.n);
 
+                // Spigot start
+                Arrays.fill( recentTps, 20 );
+                long lastTick = System.nanoTime(), catchupTime = 0, curTime, wait, tickSection = lastTick;
                 while (this.isRunning) {
-                    long i = SystemUtils.b() - this.aa;
-
-                    if (i > 2000L && this.aa - this.Q >= 15000L) {
-                        long j = i / 50L;
+                    curTime = System.nanoTime();
+                    wait = TICK_TIME - (curTime - lastTick) - catchupTime;
+                    if (wait > 0) {
+                        Thread.sleep(wait / 1000000);
+                        catchupTime = 0;
+                        continue;
+                    } else {
+                        catchupTime = Math.min(1000000000, Math.abs(wait));
+                    }
 
-                        if (server.getWarnOnOverload()) // CraftBukkit
-                        MinecraftServer.LOGGER.warn("Can\'t keep up! Is the server overloaded? Running {}ms or {} ticks behind", Long.valueOf(i), Long.valueOf(j));
-                        this.aa += j * 50L;
-                        this.Q = this.aa;
+                    if ( MinecraftServer.currentTick++ % SAMPLE_INTERVAL == 0 )
+                    {
+                        double currentTps = 1E9 / ( curTime - tickSection ) * SAMPLE_INTERVAL;
+                        recentTps[0] = calcTps( recentTps[0], 0.92, currentTps ); // 1/exp(5sec/1min)
+                        recentTps[1] = calcTps( recentTps[1], 0.9835, currentTps ); // 1/exp(5sec/5min)
+                        recentTps[2] = calcTps( recentTps[2], 0.9945, currentTps ); // 1/exp(5sec/15min)
+                        tickSection = curTime;
                     }
+                    lastTick = curTime;
 
                     MinecraftServer.currentTick = (int) (System.currentTimeMillis() / 50); // CraftBukkit
                     this.v();
                     this.aa += 50L;
-
-                    while (SystemUtils.b() < this.aa) {
-                        Thread.sleep(1L);
-                    }
-
                     this.P = true;
                 }
+                // Spigot end
             } else {
                 this.a((CrashReport) null);
             }
diff --git a/src/main/java/org/spigotmc/SpigotConfig.java b/src/main/java/org/spigotmc/SpigotConfig.java
index 5d3060c01..6096cccc1 100644
--- a/src/main/java/org/spigotmc/SpigotConfig.java
+++ b/src/main/java/org/spigotmc/SpigotConfig.java
@@ -266,4 +266,9 @@ public class SpigotConfig
             }
         }
     }
+
+    private static void tpsCommand()
+    {
+        commands.put( "tps", new TicksPerSecondCommand( "tps" ) );
+    }
 }
diff --git a/src/main/java/org/spigotmc/TicksPerSecondCommand.java b/src/main/java/org/spigotmc/TicksPerSecondCommand.java
new file mode 100644
index 000000000..be2e31dea
--- /dev/null
+++ b/src/main/java/org/spigotmc/TicksPerSecondCommand.java
@@ -0,0 +1,45 @@
+package org.spigotmc;
+
+import com.google.common.base.Joiner;
+import net.minecraft.server.MinecraftServer;
+import com.google.common.collect.Iterables;
+import org.bukkit.ChatColor;
+import org.bukkit.command.Command;
+import org.bukkit.command.CommandSender;
+
+public class TicksPerSecondCommand extends Command
+{
+
+    public TicksPerSecondCommand(String name)
+    {
+        super( name );
+        this.description = "Gets the current ticks per second for the server";
+        this.usageMessage = "/tps";
+        this.setPermission( "bukkit.command.tps" );
+    }
+
+    @Override
+    public boolean execute(CommandSender sender, String currentAlias, String[] args)
+    {
+        if ( !testPermission( sender ) )
+        {
+            return true;
+        }
+
+        StringBuilder sb = new StringBuilder( ChatColor.GOLD + "TPS from last 1m, 5m, 15m: " );
+        for ( double tps : MinecraftServer.getServer().recentTps )
+        {
+            sb.append( format( tps ) );
+            sb.append( ", " );
+        }
+        sender.sendMessage( sb.substring( 0, sb.length() - 2 ) );
+
+        return true;
+    }
+
+    private String format(double tps)
+    {
+        return ( ( tps > 18.0 ) ? ChatColor.GREEN : ( tps > 16.0 ) ? ChatColor.YELLOW : ChatColor.RED ).toString()
+                + ( ( tps > 20.0 ) ? "*" : "" ) + Math.min( Math.round( tps * 100.0 ) / 100.0, 20.0 );
+    }
+}
-- 
2.17.1