Paper/Spigot-Server-Patches/0052-Optimize-explosions.patch

From 0c565e604fa92cddf6f902ed529bb5ba315e61e4 Mon Sep 17 00:00:00 2001
From: Byteflux <byte@byteflux.net>
Date: Tue, 16 Jun 2015 05:52:58 -0700
Subject: [PATCH] Optimize explosions

The process of determining an entity's exposure from explosions can be
expensive when there are hundreds or more entities in range.

This patch adds a per-tick cache that is used for storing and retrieving
an entity's exposure during an explosion.

diff --git a/src/main/java/net/minecraft/server/Explosion.java b/src/main/java/net/minecraft/server/Explosion.java
index 0e8af2e..f6067ce 100644
--- a/src/main/java/net/minecraft/server/Explosion.java
+++ b/src/main/java/net/minecraft/server/Explosion.java
@@ -129,7 +129,7 @@ public class Explosion {
                         d8 /= d11;
                         d9 /= d11;
                         d10 /= d11;
-                        double d12 = (double) this.world.a(vec3d, entity.getBoundingBox());
+                        double d12 = this.getBlockDensity(vec3d, entity.getBoundingBox()); // PaperSpigot - Optimize explosions
                         double d13 = (1.0D - d7) * d12;
 
                         // entity.damageEntity(DamageSource.explosion(this), (float) ((int) ((d13 * d13 + d13) / 2.0D * 8.0D * (double) f3 + 1.0D)));+                        // CraftBukkit start
@@ -294,4 +294,86 @@ public class Explosion {
     public List<BlockPosition> getBlocks() {
         return this.blocks;
     }
+
+    // PaperSpigot start - Optimize explosions
+    private float getBlockDensity(Vec3D vec3d, AxisAlignedBB aabb) {
+        if (!this.world.paperSpigotConfig.optimizeExplosions) {
+            return this.world.a(vec3d, aabb);
+        }
+
+        CacheKey key = new CacheKey(this, aabb);
+        Float blockDensity = this.world.explosionDensityCache.get(key);
+        if (blockDensity == null) {
+            blockDensity = this.world.a(vec3d, aabb);
+            this.world.explosionDensityCache.put(key, blockDensity);
+        }
+
+        return blockDensity;
+    }
+
+    static class CacheKey {
+        private final World world;
+        private final double posX, posY, posZ;
+        private final double minX, minY, minZ;
+        private final double maxX, maxY, maxZ;
+
+        public CacheKey(Explosion explosion, AxisAlignedBB aabb) {
+            this.world = explosion.world;
+            this.posX = explosion.posX;
+            this.posY = explosion.posY;
+            this.posZ = explosion.posZ;
+            this.minX = aabb.a;
+            this.minY = aabb.b;
+            this.minZ = aabb.c;
+            this.maxX = aabb.d;
+            this.maxY = aabb.e;
+            this.maxZ = aabb.f;
+        }
+
+        @Override
+        public boolean equals(Object o) {
+            if (this == o) return true;
+            if (o == null || getClass() != o.getClass()) return false;
+
+            CacheKey cacheKey = (CacheKey) o;
+
+            if (Double.compare(cacheKey.posX, posX) != 0) return false;
+            if (Double.compare(cacheKey.posY, posY) != 0) return false;
+            if (Double.compare(cacheKey.posZ, posZ) != 0) return false;
+            if (Double.compare(cacheKey.minX, minX) != 0) return false;
+            if (Double.compare(cacheKey.minY, minY) != 0) return false;
+            if (Double.compare(cacheKey.minZ, minZ) != 0) return false;
+            if (Double.compare(cacheKey.maxX, maxX) != 0) return false;
+            if (Double.compare(cacheKey.maxY, maxY) != 0) return false;
+            if (Double.compare(cacheKey.maxZ, maxZ) != 0) return false;
+            return world.equals(cacheKey.world);
+        }
+
+        @Override
+        public int hashCode() {
+            int result;
+            long temp;
+            result = world.hashCode();
+            temp = Double.doubleToLongBits(posX);
+            result = 31 * result + (int) (temp ^ (temp >>> 32));
+            temp = Double.doubleToLongBits(posY);
+            result = 31 * result + (int) (temp ^ (temp >>> 32));
+            temp = Double.doubleToLongBits(posZ);
+            result = 31 * result + (int) (temp ^ (temp >>> 32));
+            temp = Double.doubleToLongBits(minX);
+            result = 31 * result + (int) (temp ^ (temp >>> 32));
+            temp = Double.doubleToLongBits(minY);
+            result = 31 * result + (int) (temp ^ (temp >>> 32));
+            temp = Double.doubleToLongBits(minZ);
+            result = 31 * result + (int) (temp ^ (temp >>> 32));
+            temp = Double.doubleToLongBits(maxX);
+            result = 31 * result + (int) (temp ^ (temp >>> 32));
+            temp = Double.doubleToLongBits(maxY);
+            result = 31 * result + (int) (temp ^ (temp >>> 32));
+            temp = Double.doubleToLongBits(maxZ);
+            result = 31 * result + (int) (temp ^ (temp >>> 32));
+            return result;
+        }
+    }
+    // PaperSpigot end
 }
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index 76ba101..c9a2ed7 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -860,6 +860,7 @@ public abstract class MinecraftServer implements Runnable, ICommandListener, IAs
                 worldserver.timings.tracker.stopTiming(); // Spigot
                 this.methodProfiler.b();
                 this.methodProfiler.b();
+                worldserver.explosionDensityCache.clear(); // PaperSpigot - Optimize explosions
             // } // CraftBukkit
 
             // this.i[i][this.ticks % 100] = System.nanoTime() - j; // CraftBukkit
diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index 4bb6feb..30d94f5 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -133,6 +133,7 @@ public abstract class World implements IBlockAccess {
     public static String blockLocation;
     private int tileTickPosition;
     public ExecutorService lightingExecutor = Executors.newSingleThreadExecutor(new ThreadFactoryBuilder().setNameFormat("PaperSpigot - Lighting Thread").build()); // PaperSpigot - Asynchronous lighting updates
+    public final Map<Explosion.CacheKey, Float> explosionDensityCache = new HashMap<Explosion.CacheKey, Float>(); // PaperSpigot - Optimize explosions
 
     public static long chunkToKey(int x, int z)
     {
diff --git a/src/main/java/org/github/paperspigot/PaperSpigotWorldConfig.java b/src/main/java/org/github/paperspigot/PaperSpigotWorldConfig.java
index 88e0644..f3228d9 100644
--- a/src/main/java/org/github/paperspigot/PaperSpigotWorldConfig.java
+++ b/src/main/java/org/github/paperspigot/PaperSpigotWorldConfig.java
@@ -338,4 +338,10 @@ public class PaperSpigotWorldConfig
     {
         fallingBlocksCollideWithSigns = getBoolean( "falling-blocks-collide-with-signs", false );
     }
+
+    public boolean optimizeExplosions;
+    private void optimizeExplosions()
+    {
+        optimizeExplosions = getBoolean( "optimize-explosions", false );
+    }
 }
-- 
2.5.1