PaperMC/CraftBukkit-Patches/0076-Highly-Optimized-Tick-Loop.patch

From 5ceb8bec0a5b6d0c209c4fec89ca28b86a34ff9e Mon Sep 17 00:00:00 2001
From: md_5 <git@md-5.net>
Date: Sat, 25 Jan 2014 14:08:35 +1100
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 4a2f084..d213ae4 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -118,6 +118,12 @@ public abstract class MinecraftServer implements ICommandListener, Runnable, IAs
     public java.util.Queue<Runnable> processQueue = new java.util.concurrent.ConcurrentLinkedQueue<Runnable>();
     public int autosavePeriod;
     // CraftBukkit end
+    // Spigot start
+    private static final int TPS = 20;
+    private 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, File file1) {
         this.d = proxy;
@@ -469,6 +475,13 @@ public abstract class MinecraftServer implements ICommandListener, Runnable, IAs
         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()) {
@@ -479,38 +492,34 @@ public abstract class MinecraftServer implements ICommandListener, Runnable, IAs
                 this.r.setServerInfo(new ServerPingServerData("1.8", 47));
                 this.a(this.r);
 
+                // Spigot start
+                Arrays.fill( recentTps, 20 );
+                long lastTick = System.nanoTime(), catchupTime = 0, curTime, wait, tickSection = lastTick;
                 while (this.isRunning) {
-                    long j = ax();
-                    long k = j - this.ab;
-
-                    if (k > 2000L && this.ab - this.R >= 15000L) {
-                        if (server.getWarnOnOverload()) // CraftBukkit
-                        MinecraftServer.LOGGER.warn("Can\'t keep up! Did the system time change, or is the server overloaded? Running {}ms behind, skipping {} tick(s)", new Object[] { Long.valueOf(k), Long.valueOf(k / 50L)});
-                        k = 2000L;
-                        this.R = this.ab;
-                    }
-
-                    if (k < 0L) {
-                        MinecraftServer.LOGGER.warn("Time ran backwards! Did the system time change?");
-                        k = 0L;
+                    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));
                     }
 
-                    i += k;
-                    this.ab = j;
-                    if (this.worlds.get(0).everyoneDeeplySleeping()) { // CraftBukkit
-                        this.y();
-                        i = 0L;
-                    } else {
-                        while (i > 50L) {
-                            MinecraftServer.currentTick = (int) (System.currentTimeMillis() / 50); // CraftBukkit
-                            i -= 50L;
-                            this.y();
-                        }
+                    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;
 
-                    Thread.sleep(Math.max(1L, 50L - i));
+                    this.y();
                     this.Q = 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 9566cfa..345a49c 100644
--- a/src/main/java/org/spigotmc/SpigotConfig.java
+++ b/src/main/java/org/spigotmc/SpigotConfig.java
@@ -261,4 +261,9 @@ public class SpigotConfig
                     "screen." );
         }
     }
+
+    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 0000000..be2e31d
--- /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 );
+    }
+}
-- 
2.1.0