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/CraftingMenu.java b/src/main/java/net/minecraft/world/inventory/CraftingMenu.java
index 7a0c1a55a211035bbca7b97293e94b04ae308bae..59220eb9e74877e18b3e015dc0d25c892f45f746 100644
--- a/src/main/java/net/minecraft/world/inventory/CraftingMenu.java
+++ b/src/main/java/net/minecraft/world/inventory/CraftingMenu.java
@@ -76,7 +76,8 @@ public class CraftingMenu extends RecipeBookMenu<CraftingContainer> {
         if (!world.isClientSide) {
             ServerPlayer entityplayer = (ServerPlayer) player;
             ItemStack itemstack = ItemStack.EMPTY;
-            Optional<RecipeHolder<CraftingRecipe>> optional = world.getServer().getRecipeManager().getRecipeFor(RecipeType.CRAFTING, craftingInventory, world);
+            final RecipeHolder<?> currentRecipe = craftingInventory.getCurrentRecipe(); // Paper - Perf: Improve mass crafting; check last recipe used first
+            Optional<RecipeHolder<CraftingRecipe>> optional = currentRecipe == null ? world.getServer().getRecipeManager().getRecipeFor(RecipeType.CRAFTING, craftingInventory, world) : world.getServer().getRecipeManager().getRecipeFor(RecipeType.CRAFTING, craftingInventory, world, currentRecipe.id()); // Paper - Perf: Improve mass crafting; check last recipe used first
 
             if (optional.isPresent()) {
                 RecipeHolder<CraftingRecipe> recipeholder = (RecipeHolder) optional.get();
diff --git a/src/main/java/net/minecraft/world/inventory/ResultSlot.java b/src/main/java/net/minecraft/world/inventory/ResultSlot.java
index fef82418358ecf19d367dafbec159bd78ea97494..f17ff5988d826c8fad68f6bf7bac1d06edae01ae 100644
--- a/src/main/java/net/minecraft/world/inventory/ResultSlot.java
+++ b/src/main/java/net/minecraft/world/inventory/ResultSlot.java
@@ -58,7 +58,7 @@ public class ResultSlot extends Slot {
     @Override
     public void onTake(Player player, ItemStack stack) {
         this.checkTakeAchievements(stack);
-        NonNullList<ItemStack> nonNullList = player.level().getRecipeManager().getRemainingItemsFor(RecipeType.CRAFTING, this.craftSlots, player.level());
+        NonNullList<ItemStack> nonNullList = player.level().getRecipeManager().getRemainingItemsFor(RecipeType.CRAFTING, this.craftSlots, player.level(), this.craftSlots.getCurrentRecipe() != null ? this.craftSlots.getCurrentRecipe().id() : null); // Paper - Perf: Improve mass crafting; check last recipe used first
 
         for (int i = 0; i < nonNullList.size(); i++) {
             ItemStack itemStack = this.craftSlots.getItem(i);
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 0126b88f60904dfbf1e29eb3b89a985061d91f91..a31326e24cb68472c81cd781c5e3041772712862 100644
--- a/src/main/java/net/minecraft/world/item/crafting/RecipeManager.java
+++ b/src/main/java/net/minecraft/world/item/crafting/RecipeManager.java
@@ -116,6 +116,7 @@ public class RecipeManager extends SimpleJsonResourceReloadListener {
             RecipeHolder<T> recipeholder = this.byKeyTyped(type, id);
 
             if (recipeholder != null && recipeholder.value().matches(inventory, world)) {
+                inventory.setCurrentRecipe(recipeholder); // Paper - Perf: Improve mass crafting
                 return Optional.of(recipeholder);
             }
         }
@@ -147,7 +148,12 @@ public class RecipeManager extends SimpleJsonResourceReloadListener {
     }
 
     public <C extends Container, T extends Recipe<C>> NonNullList<ItemStack> getRemainingItemsFor(RecipeType<T> type, C inventory, Level world) {
-        Optional<RecipeHolder<T>> optional = this.getRecipeFor(type, inventory, world);
+        // Paper start - Perf: Improve mass crafting;; check last recipe used first
+        return this.getRemainingItemsFor(type, inventory, world, null);
+    }
+    public <C extends Container, T extends Recipe<C>> NonNullList<ItemStack> getRemainingItemsFor(RecipeType<T> type, C inventory, Level world, @Nullable ResourceLocation firstToCheck) {
+        Optional<RecipeHolder<T>> optional = firstToCheck == null ? this.getRecipeFor(type, inventory, world) : this.getRecipeFor(type, inventory, world, firstToCheck);
+        // Paper end - Perf: Improve mass crafting
 
         if (optional.isPresent()) {
             return ((RecipeHolder) optional.get()).value().getRemainingItems(inventory);