From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Jake Potrebic <jake.m.potrebic@gmail.com>
Date: Sun, 13 Aug 2023 15:41:52 -0700
Subject: [PATCH] Improve performance of mass crafts

When the server crafts all available items in CraftingMenu or InventoryMenu the game
checks either 4 or 9 times for each individual craft for a matching recipe for that container.
This check can be expensive if 64 total crafts are being performed with the recipe matching logic
being run 64 * 9 + 64 times. A breakdown of those times is below. This patch caches the last matching
recipe so that it is checked first and only if it doesn't match does the rest of the matching logic run.

Shift-click crafts are processed one at a time, so shift clicking on an item in the result of a iron block craft
where all the 9 inputs are full stacks of iron will run 64 iron block crafts. For each of those crafts, the
'remaining' blocks are calculated. This is due to recipes that have leftover items like buckets. This is done
for each craft, and done once to get the full 9 leftover items which are usually air. Then 1 item is removed
from each of the 9 inputs and each time that happens, logic is triggered to update the result itemstack. So
for each craft, that logic is run 9 times (hence the 64 * 9). The + 64 is from the 64 checks for remaining items.

After this patch, the full iteration over all recipes checking for a match should run once for a full craft to find the
initial recipe match. Then that recipe will be checked first for all future recipe match checks.

diff --git a/src/main/java/net/minecraft/world/inventory/CraftingContainer.java b/src/main/java/net/minecraft/world/inventory/CraftingContainer.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/inventory/CraftingContainer.java
+++ b/src/main/java/net/minecraft/world/inventory/CraftingContainer.java
@@ -0,0 +0,0 @@ public interface CraftingContainer extends Container, StackedContentsCompatible
     List<ItemStack> getItems();
 
     // CraftBukkit start
-    default RecipeHolder<?> getCurrentRecipe() {
+    default RecipeHolder<net.minecraft.world.item.crafting.CraftingRecipe> getCurrentRecipe() { // Paper - use correct generic
         return null;
     }
 
-    default void setCurrentRecipe(RecipeHolder<?> recipe) {
+    default void setCurrentRecipe(RecipeHolder<net.minecraft.world.item.crafting.CraftingRecipe> recipe) { // Paper - use correct generic
     }
     // CraftBukkit end
 
diff --git a/src/main/java/net/minecraft/world/inventory/CraftingMenu.java b/src/main/java/net/minecraft/world/inventory/CraftingMenu.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/inventory/CraftingMenu.java
+++ b/src/main/java/net/minecraft/world/inventory/CraftingMenu.java
@@ -0,0 +0,0 @@ public class CraftingMenu extends RecipeBookMenu<CraftingInput, CraftingRecipe>
             CraftingInput craftinginput = craftingInventory.asCraftInput();
             ServerPlayer entityplayer = (ServerPlayer) player;
             ItemStack itemstack = ItemStack.EMPTY;
+            if (recipe == null) recipe = craftingInventory.getCurrentRecipe(); // Paper - Perf: Improve mass crafting; check last recipe used first
             Optional<RecipeHolder<CraftingRecipe>> optional = world.getServer().getRecipeManager().getRecipeFor(RecipeType.CRAFTING, craftinginput, world, recipe);
             craftingInventory.setCurrentRecipe(optional.orElse(null)); // CraftBukkit
 
diff --git a/src/main/java/net/minecraft/world/inventory/ResultSlot.java b/src/main/java/net/minecraft/world/inventory/ResultSlot.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/inventory/ResultSlot.java
+++ b/src/main/java/net/minecraft/world/inventory/ResultSlot.java
@@ -0,0 +0,0 @@ public class ResultSlot extends Slot {
         CraftingInput craftingInput = positioned.input();
         int i = positioned.left();
         int j = positioned.top();
-        NonNullList<ItemStack> nonNullList = player.level().getRecipeManager().getRemainingItemsFor(RecipeType.CRAFTING, craftingInput, player.level());
+        NonNullList<ItemStack> nonNullList = player.level().getRecipeManager().getRemainingItemsFor(RecipeType.CRAFTING, craftingInput, player.level(), this.craftSlots.getCurrentRecipe()); // Paper - Perf: Improve mass crafting; check last recipe used first
 
         for (int k = 0; k < craftingInput.height(); k++) {
             for (int l = 0; l < craftingInput.width(); l++) {
diff --git a/src/main/java/net/minecraft/world/inventory/TransientCraftingContainer.java b/src/main/java/net/minecraft/world/inventory/TransientCraftingContainer.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/inventory/TransientCraftingContainer.java
+++ b/src/main/java/net/minecraft/world/inventory/TransientCraftingContainer.java
@@ -0,0 +0,0 @@ public class TransientCraftingContainer implements CraftingContainer {
 
     // CraftBukkit start - add fields
     public List<HumanEntity> transaction = new java.util.ArrayList<HumanEntity>();
-    private RecipeHolder<?> currentRecipe;
+    private RecipeHolder<net.minecraft.world.item.crafting.CraftingRecipe> currentRecipe; // Paper - use correct generic
     public Container resultInventory;
     private Player owner;
     private int maxStack = MAX_STACK;
@@ -0,0 +0,0 @@ public class TransientCraftingContainer implements CraftingContainer {
     }
 
     @Override
-    public RecipeHolder<?> getCurrentRecipe() {
+    public RecipeHolder<net.minecraft.world.item.crafting.CraftingRecipe> getCurrentRecipe() { // Paper - use correct generic
         return this.currentRecipe;
     }
 
     @Override
-    public void setCurrentRecipe(RecipeHolder<?> currentRecipe) {
+    public void setCurrentRecipe(RecipeHolder<net.minecraft.world.item.crafting.CraftingRecipe> currentRecipe) { // Paper - use correct generic
         this.currentRecipe = currentRecipe;
     }
 
diff --git a/src/main/java/net/minecraft/world/item/crafting/RecipeManager.java b/src/main/java/net/minecraft/world/item/crafting/RecipeManager.java
index 0000000000000000000000000000000000000000..0000000000000000000000000000000000000000 100644
--- a/src/main/java/net/minecraft/world/item/crafting/RecipeManager.java
+++ b/src/main/java/net/minecraft/world/item/crafting/RecipeManager.java
@@ -0,0 +0,0 @@ public class RecipeManager extends SimpleJsonResourceReloadListener {
     }
 
     public <I extends RecipeInput, T extends Recipe<I>> Optional<RecipeHolder<T>> getRecipeFor(RecipeType<T> type, I input, Level world, @Nullable RecipeHolder<T> recipe) {
-        // CraftBukkit start
-        List<RecipeHolder<T>> list = this.byType(type).stream().filter((recipeholder1) -> {
-            return recipeholder1.value().matches(input, world);
-        }).toList();
-        Optional<RecipeHolder<T>> recipe1 = (list.isEmpty() || input.isEmpty()) ? Optional.empty() : (recipe != null && recipe.value().matches(input, world) ? Optional.of(recipe) : Optional.of(list.getLast())); // CraftBukkit - SPIGOT-4638: last recipe gets priority
-        return recipe1;
-        // CraftBukkit end
+        // Paper start - fix upstream's complete screw up of checking last used recipe
+        if (input.isEmpty()) {
+            return Optional.empty();
+        } else if (recipe != null && recipe.value().matches(input, world)) {
+            return Optional.of(recipe);
+        } else {
+            // CraftBukkit start
+            List<RecipeHolder<T>> list = this.byType(type).stream().filter((recipeholder1) -> {
+                return recipeholder1.value().matches(input, world);
+            }).toList();
+            return list.isEmpty() ? Optional.empty() : Optional.of(list.getLast()); // CraftBukkit - SPIGOT-4638: last recipe gets priority
+            // CraftBukkit end
+        }
+        // Paper end
     }
 
     public <I extends RecipeInput, T extends Recipe<I>> List<RecipeHolder<T>> getAllRecipesFor(RecipeType<T> type) {
@@ -0,0 +0,0 @@ public class RecipeManager extends SimpleJsonResourceReloadListener {
     }
 
     public <I extends RecipeInput, T extends Recipe<I>> NonNullList<ItemStack> getRemainingItemsFor(RecipeType<T> type, I input, Level world) {
-        Optional<RecipeHolder<T>> optional = this.getRecipeFor(type, input, world);
+        // Paper start - Perf: improve performance of mass crafts
+        return this.getRemainingItemsFor(type, input, world, null);
+    }
+    public <I extends RecipeInput, T extends Recipe<I>> NonNullList<ItemStack> getRemainingItemsFor(RecipeType<T> type, I input, Level world, @Nullable RecipeHolder<T> previousRecipe) {
+        Optional<RecipeHolder<T>> optional = this.getRecipeFor(type, input, world, previousRecipe);
+        // Paper end - Perf: improve performance of mass crafts
 
         if (optional.isPresent()) {
             return ((RecipeHolder) optional.get()).value().getRemainingItems(input);
