From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: 2No2Name <2No2Name@web.de>
Date: Wed, 15 Dec 2021 11:20:48 -0500
Subject: [PATCH] lithium: fast retrieval

Original code by CaffeineMC, licensed under GNU Lesser General Public License v3.0
You can find the original code on https://github.com/CaffeineMC/lithium-fabric (Yarn mappings)

diff --git a/src/main/java/net/minecraft/world/level/entity/EntitySectionStorage.java b/src/main/java/net/minecraft/world/level/entity/EntitySectionStorage.java
index 74210dc2eef63da7360b1f833bb59b278419fb2b..aae1f6d5d0e47363042657d755f6bfeea2420347 100644
--- a/src/main/java/net/minecraft/world/level/entity/EntitySectionStorage.java
+++ b/src/main/java/net/minecraft/world/level/entity/EntitySectionStorage.java
@@ -32,33 +32,44 @@ public class EntitySectionStorage<T extends EntityAccess> {
         this.intialSectionVisibility = chunkStatusDiscriminator;
     }
 
+    // JettPack start - lithium: fast retrieval
     public void forEachAccessibleNonEmptySection(AABB box, Consumer<EntitySection<T>> action) {
-        int i = SectionPos.posToSectionCoord(box.minX - 2.0D);
-        int j = SectionPos.posToSectionCoord(box.minY - 2.0D);
-        int k = SectionPos.posToSectionCoord(box.minZ - 2.0D);
-        int l = SectionPos.posToSectionCoord(box.maxX + 2.0D);
-        int m = SectionPos.posToSectionCoord(box.maxY + 2.0D);
-        int n = SectionPos.posToSectionCoord(box.maxZ + 2.0D);
-
-        for(int o = i; o <= l; ++o) {
-            long p = SectionPos.asLong(o, 0, 0);
-            long q = SectionPos.asLong(o, -1, -1);
-            LongIterator longIterator = this.sectionIds.subSet(p, q + 1L).iterator();
-
-            while(longIterator.hasNext()) {
-                long r = longIterator.nextLong();
-                int s = SectionPos.y(r);
-                int t = SectionPos.z(r);
-                if (s >= j && s <= m && t >= k && t <= n) {
-                    EntitySection<T> entitySection = this.sections.get(r);
-                    if (entitySection != null && !entitySection.isEmpty() && entitySection.getStatus().isAccessible()) {
-                        action.accept(entitySection);
-                    }
-                }
+        int minX = SectionPos.posToSectionCoord(box.minX - 2.0D);
+        int minY = SectionPos.posToSectionCoord(box.minY - 2.0D);
+        int minZ = SectionPos.posToSectionCoord(box.minZ - 2.0D);
+        int maxX = SectionPos.posToSectionCoord(box.maxX + 2.0D);
+        int maxY = SectionPos.posToSectionCoord(box.maxY + 2.0D);
+        int maxZ = SectionPos.posToSectionCoord(box.maxZ + 2.0D);
+
+        for (int x = minX; x <= maxX; x++) {
+            for (int z = Math.max(minZ, 0); z <= maxZ; z++) {
+                this.forEachInColumn(x, minY, maxY, z, action);
             }
+
+            int bound = Math.min(-1, maxZ);
+            for (int z = minZ; z <= bound; z++) {
+                this.forEachInColumn(x, minY, maxY, z, action);
+            }
+        }
+    }
+
+    private void forEachInColumn(int x, int minY, int maxY, int z, Consumer<EntitySection<T>> action) {
+        for (int y = Math.max(minY, 0); y <= maxY; y++) {
+            this.consumeSection(x, y, z, action);
+        }
+        int bound = Math.min(-1, maxY);
+        for (int y = minY; y <= bound; y++) {
+            this.consumeSection(x, y, z, action);
         }
+    }
 
+    private void consumeSection(int x, int y, int z, Consumer<EntitySection<T>> action) {
+        EntitySection<T> section = this.getSection(SectionPos.asLong(x, y, z));
+        if (section != null && section.getStatus().isAccessible()) {
+            action.accept(section);
+        }
     }
+    // JettPack end
 
     public LongStream getExistingSectionPositionsInChunk(long chunkPos) {
         int i = ChunkPos.getX(chunkPos);