Paper/patches/server-remapped/0369-Avoid-hopper-searches-if-there-are-no-items.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: CullanP <cullanpage@gmail.com>
Date: Thu, 3 Mar 2016 02:13:38 -0600
Subject: [PATCH] Avoid hopper searches if there are no items

Hoppers searching for items and minecarts is the most expensive part of hopper ticking.
We keep track of the number of minecarts and items in a chunk.
If there are no items in the chunk, we skip searching for items.
If there are no minecarts in the chunk, we skip searching for them.

Usually hoppers aren't near items, so we can skip most item searches.
And since minecart hoppers are used _very_ rarely near we can avoid alot of searching there.

Combined, this adds up a lot.

diff --git a/src/main/java/net/minecraft/world/entity/EntitySelector.java b/src/main/java/net/minecraft/world/entity/EntitySelector.java
index d3640975c5a33b4911428760691215905b987385..e7facd849e3511c64b4ae44b34382f4a4985f2a4 100644
--- a/src/main/java/net/minecraft/world/entity/EntitySelector.java
+++ b/src/main/java/net/minecraft/world/entity/EntitySelector.java
@@ -16,6 +16,7 @@ public final class EntitySelector {
     public static final Predicate<Entity> ENTITY_NOT_BEING_RIDDEN = (entity) -> {
         return entity.isAlive() && !entity.isVehicle() && !entity.isPassenger();
     };
+    public static final Predicate<Entity> isInventory() { return CONTAINER_ENTITY_SELECTOR; } // Paper - OBFHELPER
     public static final Predicate<Entity> CONTAINER_ENTITY_SELECTOR = (entity) -> {
         return entity instanceof Container && entity.isAlive();
     };
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 85861545ec4620a6cfd06876dad091637bd29b0b..4fef3abe4b416cbebe1b456468b5c3e162de18f1 100644
--- a/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
+++ b/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
@@ -31,10 +31,13 @@ import net.minecraft.server.level.ChunkHolder;
 import net.minecraft.server.level.ServerChunkCache;
 import net.minecraft.server.level.ServerLevel;
 import net.minecraft.util.Mth;
+import net.minecraft.world.Container;
 import net.minecraft.world.entity.Entity;
+import net.minecraft.world.entity.EntitySelector;
 import net.minecraft.world.entity.EntityType;
 import net.minecraft.world.entity.boss.EnderDragonPart;
 import net.minecraft.world.entity.boss.enderdragon.EnderDragon;
+import net.minecraft.world.entity.item.ItemEntity;
 import net.minecraft.world.level.ChunkPos;
 import net.minecraft.world.level.ChunkTickList;
 import net.minecraft.world.level.EmptyTickList;
@@ -122,6 +125,10 @@ public class LevelChunk implements ChunkAccess {
             return removed;
         }
     }
+    // Track the number of minecarts and items
+    // Keep this synced with entitySlices.add() and entitySlices.remove()
+    private final int[] itemCounts = new int[16];
+    private final int[] inventoryEntityCounts = new int[16];
     // Paper end
 
     public LevelChunk(Level world, ChunkPos pos, ChunkBiomeContainer biomes, UpgradeData upgradeData, TickList<Block> blockTickScheduler, TickList<Fluid> fluidTickScheduler, long inhabitedTime, @Nullable LevelChunkSection[] sections, @Nullable Consumer<LevelChunk> loadToWorldConsumer) {
@@ -581,6 +588,13 @@ public class LevelChunk implements ChunkAccess {
         entity.zChunk = this.chunkPos.z;
         this.entities.add(entity); // Paper - per chunk entity list
         this.entitySlices[k].add(entity);
+        // Paper start
+        if (entity instanceof ItemEntity) {
+            itemCounts[k]++;
+        } else if (entity instanceof Container) {
+            inventoryEntityCounts[k]++;
+        }
+        // Paper end
         entity.entitySlice = this.entitySlices[k]; // Paper
         this.markUnsaved(); // Paper
     }
@@ -614,6 +628,11 @@ public class LevelChunk implements ChunkAccess {
         if (!this.entitySlices[section].remove(entity)) {
             return;
         }
+        if (entity instanceof ItemEntity) {
+            itemCounts[section]--;
+        } else if (entity instanceof Container) {
+            inventoryEntityCounts[section]--;
+        }
         entityCounts.decrement(entity.getMinecraftKeyString());
         this.markUnsaved(); // Paper
         // Paper end
@@ -899,6 +918,14 @@ public class LevelChunk implements ChunkAccess {
         for (int k = i; k <= j; ++k) {
             Iterator iterator = this.entitySlices[k].iterator(); // Spigot
 
+            // Paper start - Don't search for inventories if we have none, and that is all we want
+            /*
+             * We check if they want inventories by seeing if it is the static `IEntitySelector.d`
+             *
+             * Make sure the inventory selector stays in sync.
+             * It should be the one that checks `var1 instanceof IInventory && var1.isAlive()`
+             */
+            if (predicate == EntitySelector.isInventory() && inventoryEntityCounts[k] <= 0) continue;
             while (iterator.hasNext()) {
                 T entity = (T) iterator.next(); // CraftBukkit - decompile error
                 if (entity.shouldBeRemoved) continue; // Paper
@@ -919,9 +946,29 @@ public class LevelChunk implements ChunkAccess {
         i = Mth.clamp(i, 0, this.entitySlices.length - 1);
         j = Mth.clamp(j, 0, this.entitySlices.length - 1);
 
+        // Paper start
+        int[] counts;
+        if (ItemEntity.class.isAssignableFrom(entityClass)) {
+            counts = itemCounts;
+        } else if (Container.class.isAssignableFrom(entityClass)) {
+            counts = inventoryEntityCounts;
+        } else {
+            counts = null;
+        }
+        // Paper end
         for (int k = i; k <= j; ++k) {
+            if (counts != null && counts[k] <= 0) continue; // Paper - Don't check a chunk if it doesn't have the type we are looking for
             Iterator iterator = this.entitySlices[k].iterator(); // Spigot
 
+            // Paper start - Don't search for inventories if we have none, and that is all we want
+            /*
+             * We check if they want inventories by seeing if it is the static `IEntitySelector.d`
+             *
+             * Make sure the inventory selector stays in sync.
+             * It should be the one that checks `var1 instanceof IInventory && var1.isAlive()`
+             */
+            if (predicate == EntitySelector.isInventory() && inventoryEntityCounts[k] <= 0) continue;
+            // Paper end
             while (iterator.hasNext()) {
                 T t0 = (T) iterator.next(); // CraftBukkit - decompile error
                 if (t0.shouldBeRemoved) continue; // Paper