Use BigDecimal to improve accracy of TPS results - long live 20 TPS!

It's always been commonly said to 'ignore' that TPS was '19.X', that it was fine. I suspect that the inaccuracy of floating point math resulted in us losing precision over time, making it difficult to actually get back to 20, as you know the fun 0.1 + 0.1 ... 9 more times != 1 problem. BigDecimal supports working with doubles with higher precision. This change makes it so our RollingAverage class maintains all of the data using BigDecimal and using BigDecimal arithematic operations. This ensures we have extremely high precision, enabling us to actually be able print '20 TPS' when TPS is perfect.
2025-03-13 19:28:03 +01:00 · 2018-09-17 22:32:37 -04:00 · 2018-09-17 22:32:37 -04:00 · bf7742bf96
commit bf7742bf96
parent af737481c2
11 changed files with 31 additions and 27 deletions
--- a/Spigot-Server-Patches/Add-Early-Warning-Feature-to-WatchDog.patch
+++ b/Spigot-Server-Patches/Add-Early-Warning-Feature-to-WatchDog.patch
@ -37,7 +37,7 @@ index cc2e4ad3bd..54f088c242 100644
     public static int tabSpamLimit = 500;
     private static void tabSpamLimiters() {
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 2e9836d8f9..8b8cbde2b9 100644
+index 18eeee5106..6fa54386e8 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
--- a/Spigot-Server-Patches/Auto-Save-Improvements.patch
+++ b/Spigot-Server-Patches/Auto-Save-Improvements.patch
@ -96,7 +96,7 @@ index 3c9c3cd41d..8d1264879b 100644
 
     public boolean isEmpty() {
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index 7417660e4d..7a972f4187 100644
+index 9739288b53..a35eac043c 100644
 --- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
 +++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
@@ -0,0 +0,0 @@ public class ChunkProviderServer implements IChunkProvider {
@ -109,7 +109,7 @@ index 7417660e4d..7a972f4187 100644
                     }
                 }
 diff --git a/src/main/java/net/minecraft/server/EntityPlayer.java b/src/main/java/net/minecraft/server/EntityPlayer.java
-index faf733f824..c6903559ef 100644
+index 3d83900298..690cff8828 100644
 --- a/src/main/java/net/minecraft/server/EntityPlayer.java
 +++ b/src/main/java/net/minecraft/server/EntityPlayer.java
@@ -0,0 +0,0 @@ public class EntityPlayer extends EntityHuman implements ICrafting {
@ -121,7 +121,7 @@ index faf733f824..c6903559ef 100644
     public final MinecraftServer server;
     public final PlayerInteractManager playerInteractManager;
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 13d3315b9c..a367cbf52b 100644
+index 04d8c108b4..a547ee5ca1 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
@ -207,7 +207,7 @@ index 02dbb8c6c3..73d72ef7e3 100644
     public WhiteList getWhitelist() {
         return this.whitelist;
 diff --git a/src/main/java/net/minecraft/server/WorldServer.java b/src/main/java/net/minecraft/server/WorldServer.java
-index 4be3a6ae94..59b5a04581 100644
+index c5201697d5..ca2e027cda 100644
 --- a/src/main/java/net/minecraft/server/WorldServer.java
 +++ b/src/main/java/net/minecraft/server/WorldServer.java
@@ -0,0 +0,0 @@ public class WorldServer extends World implements IAsyncTaskHandler {
--- a/Spigot-Server-Patches/Basic-PlayerProfile-API.patch
+++ b/Spigot-Server-Patches/Basic-PlayerProfile-API.patch
@ -429,7 +429,7 @@ index dce1417aff..f7856897f6 100644
      * Calculates distance between 2 entities
      * @param e1
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 464db5ebb8..3e99221619 100644
+index 6a3d5fdff4..65204c259e 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
--- a/Spigot-Server-Patches/Fix-major-memory-leaks-in-ExpiringMap.patch
+++ b/Spigot-Server-Patches/Fix-major-memory-leaks-in-ExpiringMap.patch
@ -180,7 +180,7 @@ index 4006f5a69c..d64c143017 100644
     }
 
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 80e8b023cf..70a609efcc 100644
+index eb3fc836fb..81cda5df56 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
--- a/Spigot-Server-Patches/Further-improve-server-tick-loop.patch
+++ b/Spigot-Server-Patches/Further-improve-server-tick-loop.patch
@ -12,7 +12,7 @@ Previous implementation did not calculate TPS correctly.
 Switch to a realistic rolling average and factor in std deviation as an extra reporting variable

 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 788f0519a8..13c6021ffa 100644
+index 788f0519a8..d6ea4ae532 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
@ -59,39 +59,43 @@ index 788f0519a8..13c6021ffa 100644
 +    public static class RollingAverage {
 +        private final int size;
 +        private long time;
-+        private double total;
+        private java.math.BigDecimal total;
 +        private int index = 0;
-+        private final double[] samples;
+        private final java.math.BigDecimal[] samples;
 +        private final long[] times;
 +
 +        RollingAverage(int size) {
 +            this.size = size;
 +            this.time = size * SEC_IN_NANO;
-+            this.total = TPS * SEC_IN_NANO * size;
-+            this.samples = new double[size];
+            this.total = dec(TPS).multiply(dec(SEC_IN_NANO)).multiply(dec(size));
+            this.samples = new java.math.BigDecimal[size];
 +            this.times = new long[size];
 +            for (int i = 0; i < size; i++) {
-+                this.samples[i] = TPS;
+                this.samples[i] = dec(TPS);
 +                this.times[i] = SEC_IN_NANO;
 +            }
 +        }
 +
-+        public void add(double x, long t) {
+        private static java.math.BigDecimal dec(long t) {
+            return new java.math.BigDecimal(t);
+        }
+        public void add(java.math.BigDecimal x, long t) {
 +            time -= times[index];
-+            total -= samples[index] * times[index];
+            total = total.subtract(samples[index].multiply(dec(times[index])));
 +            samples[index] = x;
 +            times[index] = t;
 +            time += t;
-+            total += x * t;
+            total = total.add(x.multiply(dec(t)));
 +            if (++index == size) {
 +                index = 0;
 +            }
 +        }
 +
 +        public double getAverage() {
-+            return total / time;
+            return total.divide(dec(time), 30, java.math.RoundingMode.HALF_UP).doubleValue();
 +        }
 +    }
+    private static final java.math.BigDecimal TPS_BASE = new java.math.BigDecimal(1E9).multiply(new java.math.BigDecimal(SAMPLE_INTERVAL));
 +    // Paper End
     // Spigot End
 
@ -138,7 +142,7 @@ index 788f0519a8..13c6021ffa 100644
 -                        recentTps[1] = calcTps( recentTps[1], 0.9835, currentTps ); // 1/exp(5sec/5min)
 -                        recentTps[2] = calcTps( recentTps[2], 0.9945, currentTps ); // 1/exp(5sec/15min)
 +                        final long diff = curTime - tickSection;
-+                        double currentTps = 1E9 / diff * SAMPLE_INTERVAL;
+                        java.math.BigDecimal currentTps = TPS_BASE.divide(new java.math.BigDecimal(diff), 30, java.math.RoundingMode.HALF_UP);
 +                        tps1.add(currentTps, diff);
 +                        tps5.add(currentTps, diff);
 +                        tps15.add(currentTps, diff);
--- a/Spigot-Server-Patches/Implement-extended-PaperServerListPingEvent.patch
+++ b/Spigot-Server-Patches/Implement-extended-PaperServerListPingEvent.patch
@ -177,7 +177,7 @@ index 0000000000..350410527b
 +
 +}
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 3e99221619..2e9836d8f9 100644
+index 65204c259e..18eeee5106 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@
--- a/Spigot-Server-Patches/Lighting-Queue.patch
+++ b/Spigot-Server-Patches/Lighting-Queue.patch
@ -102,7 +102,7 @@ index 4622e92b05..d4bebddab0 100644
 
         IMMEDIATE, QUEUED, CHECK;
 diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
-index 0034956af9..1379b574ef 100644
+index 68212aa26e..046973a4ed 100644
 --- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
 +++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
@@ -0,0 +0,0 @@ public class ChunkProviderServer implements IChunkProvider {
@ -114,7 +114,7 @@ index 0034956af9..1379b574ef 100644
         // Update neighbor counts
         for (int x = -2; x < 3; x++) {
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 13c6021ffa..30541dfa5a 100644
+index d6ea4ae532..5086fe4027 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
@ -233,7 +233,7 @@ index 0000000000..60562f1fd2
 +    }
 +}
 diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
-index 929875340f..0fe8a97f24 100644
+index 499d64ea2c..e06da6bef9 100644
 --- a/src/main/java/net/minecraft/server/World.java
 +++ b/src/main/java/net/minecraft/server/World.java
@@ -0,0 +0,0 @@ public abstract class World implements IEntityAccess, GeneratorAccess, IIBlockAc
--- a/Spigot-Server-Patches/Optimize-Hoppers.patch
+++ b/Spigot-Server-Patches/Optimize-Hoppers.patch
@ -47,7 +47,7 @@ index 9326eaa2a9..4641113f9d 100644
         itemstack.d(this.B());
         if (this.tag != null) {
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 8b8cbde2b9..80e8b023cf 100644
+index 6fa54386e8..eb3fc836fb 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
--- a/Spigot-Server-Patches/Optimize-explosions.patch
+++ b/Spigot-Server-Patches/Optimize-explosions.patch
@ -124,7 +124,7 @@ index 2620c4c2bd..a31e07b903 100644
 +    // Paper end
 }
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 30541dfa5a..bbd476bb0e 100644
+index 5086fe4027..abed6bb977 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@ public abstract class MinecraftServer implements IAsyncTaskHandler, IMojangStati
@ -136,7 +136,7 @@ index 30541dfa5a..bbd476bb0e 100644
         }
 
 diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
-index 0fe8a97f24..c8b9c10f12 100644
+index e06da6bef9..c823cef341 100644
 --- a/src/main/java/net/minecraft/server/World.java
 +++ b/src/main/java/net/minecraft/server/World.java
@@ -0,0 +0,0 @@ import org.apache.logging.log4j.Logger;
--- a/Spigot-Server-Patches/Use-TerminalConsoleAppender-for-console-improvements.patch
+++ b/Spigot-Server-Patches/Use-TerminalConsoleAppender-for-console-improvements.patch
@ -185,7 +185,7 @@ index dabad6b055..fc7e244f8b 100644
         System.setOut(new PrintStream(new LoggerOutputStream(logger, Level.INFO), true));
         System.setErr(new PrintStream(new LoggerOutputStream(logger, Level.WARN), true));
 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 08ce98d071..464db5ebb8 100644
+index 8d345a0502..6a3d5fdff4 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@ import org.apache.commons.lang3.Validate;
--- a/Spigot-Server-Patches/remove-null-possibility-for-getServer-singleton.patch
+++ b/Spigot-Server-Patches/remove-null-possibility-for-getServer-singleton.patch
@ -6,7 +6,7 @@ Subject: [PATCH] remove null possibility for getServer singleton
 to stop IDE complaining about potential NPE

 diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
-index 9675d5a100..ca5e4cd65a 100644
+index 74c84dda69..eb6ada935f 100644
 --- a/src/main/java/net/minecraft/server/MinecraftServer.java
 +++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -0,0 +0,0 @@ import co.aikar.timings.MinecraftTimings; // Paper