SparklyPaperMC/patches/server/0009-Optimize-random-calls-in-chunk-ticking.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Paul Sauve <paul@technove.co>
Date: Thu, 7 Jan 2021 11:49:36 -0600
Subject: [PATCH] Optimize random calls in chunk ticking

Especially at over 30,000 chunks these random calls are fairly heavy. We
use a different method here for checking lightning, and for checking
ice.

Lightning: Each chunk now keeps an int of how many ticks until the
lightning should strike. This int is a random number from 0 to 100000 * 2,
the multiplication is required to keep the probability the same.

Ice and snow: We just generate a single random number 0-16 and increment
it, while checking if it's 0 for the current chunk.

Depending on configuration for things that tick in a chunk, this is a
5-10% improvement.

Airplane
Copyright (C) 2020 Technove LLC

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it under the terms of the GNU General Public License as published by
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but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
GNU General Public License for more details.

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diff --git a/src/main/java/net/minecraft/server/level/ServerChunkCache.java b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
index 7470f3ba66c2e894b5a5b0ba392ecabf8b04aff9..35f27e9a7c82eaec5b4a1a71696dac8485b2cd6d 100644
--- a/src/main/java/net/minecraft/server/level/ServerChunkCache.java
+++ b/src/main/java/net/minecraft/server/level/ServerChunkCache.java
@@ -983,6 +983,7 @@ public class ServerChunkCache extends ChunkSource {
             }
             // Paper end - optimize isOutisdeRange
             this.level.getProfiler().push("pollingChunks");
+            this.level.resetIceAndSnowTick(); // Airplane - reset ice & snow tick random
             int k = this.level.getGameRules().getInt(GameRules.RULE_RANDOMTICKING);
             boolean flag2 = level.ticksPerAnimalSpawns != 0L && worlddata.getGameTime() % level.ticksPerAnimalSpawns == 0L; // CraftBukkit
 
diff --git a/src/main/java/net/minecraft/server/level/ServerLevel.java b/src/main/java/net/minecraft/server/level/ServerLevel.java
index cebaf0fb8187335ca303621a2cb412bb22584e23..bc1a9981a769f3126efd453ee6bd4f5f32690fc8 100644
--- a/src/main/java/net/minecraft/server/level/ServerLevel.java
+++ b/src/main/java/net/minecraft/server/level/ServerLevel.java
@@ -833,6 +833,8 @@ public class ServerLevel extends Level implements WorldGenLevel {
     private final io.papermc.paper.util.math.ThreadUnsafeRandom randomTickRandom = new io.papermc.paper.util.math.ThreadUnsafeRandom();
     // Paper end
 
+    private int currentIceAndSnowTick = 0; protected void resetIceAndSnowTick() { this.currentIceAndSnowTick = this.randomTickRandom.nextInt(16); } // Airplane
+
     public void tickChunk(LevelChunk chunk, int randomTickSpeed) {
         ChunkPos chunkcoordintpair = chunk.getPos();
         boolean flag = this.isRaining();
@@ -843,7 +845,7 @@ public class ServerLevel extends Level implements WorldGenLevel {
         gameprofilerfiller.push("thunder");
         final BlockPos.MutableBlockPos blockposition = this.chunkTickMutablePosition; // Paper - use mutable to reduce allocation rate, final to force compile fail on change
 
-        if (!this.paperConfig.disableThunder && flag && this.isThundering() && this.random.nextInt(100000) == 0) { // Paper - Disable thunder
+        if (!this.paperConfig.disableThunder && flag && this.isThundering() && chunk.shouldDoLightning(this.random)) { // Paper - Disable thunder // Airplane - replace random with shouldDoLightning
             blockposition.set(this.findLightningTargetAround(this.getBlockRandomPos(j, 0, k, 15))); // Paper
             if (this.isRainingAt(blockposition)) {
                 DifficultyInstance difficultydamagescaler = this.getCurrentDifficultyAt(blockposition);
@@ -867,7 +869,7 @@ public class ServerLevel extends Level implements WorldGenLevel {
         }
 
         gameprofilerfiller.popPush("iceandsnow");
-         if (!this.paperConfig.disableIceAndSnow && this.randomTickRandom.nextInt(16) == 0) { // Paper - Disable ice and snow // Paper - optimise random ticking
+         if (!this.paperConfig.disableIceAndSnow && (this.currentIceAndSnowTick++ & 15) == 0) { // Paper - Disable ice and snow // Paper - optimise random ticking  // Airplane - optimize further random ticking
             // Paper start - optimise chunk ticking
             this.getRandomBlockPosition(j, 0, k, 15, blockposition);
             int normalY = chunk.getHeight(Heightmap.Types.MOTION_BLOCKING, blockposition.getX() & 15, blockposition.getZ() & 15) + 1;
diff --git a/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java b/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
index 86686c24b0b7de4b4bfadbc77419a8872a8e86ee..ff0fab668801d0b32abffbfedc7eb24abf71fed0 100644
--- a/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
+++ b/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
@@ -172,6 +172,18 @@ public class LevelChunk implements ChunkAccess {
     }
     // Paper end - rewrite light engine
 
+    // Airplane start - instead of using a random every time the chunk is ticked, define when lightning strikes preemptively
+    private int lightningTick;
+   // shouldDoLightning compiles down to 29 bytes, which with the default of 35 byte inlining should guarantee an inline
+    public final boolean shouldDoLightning(java.util.Random random) {
+        if (this.lightningTick-- <= 0) {
+            this.lightningTick = random.nextInt(100000) << 1;
+            return true;
+        }
+        return false;
+    }
+    // Airplane end
+
     public LevelChunk(Level world, ChunkPos pos, ChunkBiomeContainer biomes) {
         this(world, pos, biomes, UpgradeData.EMPTY, EmptyTickList.empty(), EmptyTickList.empty(), 0L, (LevelChunkSection[]) null, (Consumer) null);
     }
@@ -220,6 +232,7 @@ public class LevelChunk implements ChunkAccess {
         this.postProcessing = new ShortList[world.getSectionsCount()];
         // CraftBukkit start
         this.bukkitChunk = new org.bukkit.craftbukkit.CraftChunk(this);
+        this.lightningTick = this.level.random.nextInt(100000) << 1; // Airplane - initialize lightning tick
     }
 
     public org.bukkit.Chunk bukkitChunk;