Paper/patches/server/0903-Optimize-Hoppers.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Wed, 27 Apr 2016 22:09:52 -0400
Subject: [PATCH] Optimize Hoppers

* Removes unnecessary extra calls to .update() that are very expensive
* Lots of itemstack cloning removed. Only clone if the item is actually moved
* Return true when a plugin cancels inventory move item event instead of false, as false causes pulls to cycle through all items.
  However, pushes do not exhibit the same behavior, so this is not something plugins could of been relying on.
* Add option (Default on) to cooldown hoppers when they fail to move an item due to full inventory
* Skip subsequent InventoryMoveItemEvents if a plugin does not use the item after first event fire for an iteration by tracking changes to the event via an internal event implementation.
* Don't check for Entities with Inventories if the block above us is also occluding (not just Inventoried)
* Remove Streams from Item Suck In and restore restore 1.12 AABB checks which is simpler and no voxel allocations (was doing TWO Item Suck ins)

diff --git a/src/main/java/io/papermc/paper/event/inventory/PaperInventoryMoveItemEvent.java b/src/main/java/io/papermc/paper/event/inventory/PaperInventoryMoveItemEvent.java
new file mode 100644
index 0000000000000000000000000000000000000000..5c42823726e70ce6c9d0121d074315488e8b3f60
--- /dev/null
+++ b/src/main/java/io/papermc/paper/event/inventory/PaperInventoryMoveItemEvent.java
@@ -0,0 +1,31 @@
+package io.papermc.paper.event.inventory;
+
+import org.bukkit.event.inventory.InventoryMoveItemEvent;
+import org.bukkit.inventory.Inventory;
+import org.bukkit.inventory.ItemStack;
+import org.checkerframework.checker.nullness.qual.NonNull;
+import org.checkerframework.framework.qual.DefaultQualifier;
+import org.jetbrains.annotations.NotNull;
+
+@DefaultQualifier(NonNull.class)
+public class PaperInventoryMoveItemEvent extends InventoryMoveItemEvent {
+
+    public boolean calledSetItem;
+    public boolean calledGetItem;
+
+    public PaperInventoryMoveItemEvent(final @NotNull Inventory sourceInventory, final @NotNull ItemStack itemStack, final @NotNull Inventory destinationInventory, final boolean didSourceInitiate) {
+        super(sourceInventory, itemStack, destinationInventory, didSourceInitiate);
+    }
+
+    @Override
+    public ItemStack getItem() {
+        this.calledGetItem = true;
+        return super.getItem();
+    }
+
+    @Override
+    public void setItem(final ItemStack itemStack) {
+        super.setItem(itemStack);
+        this.calledSetItem = true;
+    }
+}
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index 7c9f7aefc59ae1a785b261f80f25d3304f3bdd22..45f7e7efa8cf407cae2db657074478565590bd12 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -1672,6 +1672,7 @@ public abstract class MinecraftServer extends ReentrantBlockableEventLoop<TickTa
         while (iterator.hasNext()) {
             ServerLevel worldserver = (ServerLevel) iterator.next();
             worldserver.hasPhysicsEvent =  org.bukkit.event.block.BlockPhysicsEvent.getHandlerList().getRegisteredListeners().length > 0; // Paper
+            net.minecraft.world.level.block.entity.HopperBlockEntity.skipHopperEvents = worldserver.paperConfig().hopper.disableMoveEvent || org.bukkit.event.inventory.InventoryMoveItemEvent.getHandlerList().getRegisteredListeners().length == 0; // Paper - Perf: Optimize Hoppers
             worldserver.hasEntityMoveEvent =  io.papermc.paper.event.entity.EntityMoveEvent.getHandlerList().getRegisteredListeners().length > 0; // Paper
 
             this.profiler.push(() -> {
diff --git a/src/main/java/net/minecraft/world/item/ItemStack.java b/src/main/java/net/minecraft/world/item/ItemStack.java
index 80682ce58d0b0ce0409d162f447b585163c36753..9f1dfb6c7c44d0525792d3517bfdad6479fb12a7 100644
--- a/src/main/java/net/minecraft/world/item/ItemStack.java
+++ b/src/main/java/net/minecraft/world/item/ItemStack.java
@@ -749,10 +749,16 @@ public final class ItemStack {
     }
 
     public ItemStack copy() {
-        if (this.isEmpty()) {
+        // Paper start - Perf: Optimize Hoppers
+        return this.copy(false);
+    }
+
+    public ItemStack copy(boolean originalItem) {
+        if (!originalItem && this.isEmpty()) {
+            // Paper end - Perf: Optimize Hoppers
             return ItemStack.EMPTY;
         } else {
-            ItemStack itemstack = new ItemStack(this.getItem(), this.count);
+            ItemStack itemstack = new ItemStack(originalItem ? this.item : this.getItem(), this.count); // Paper - Perf: Optimize Hoppers
 
             itemstack.setPopTime(this.getPopTime());
             if (this.tag != null) {
diff --git a/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java b/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java
index 5bdad1866386908b9fef74d15862eb107fabe68f..a6f47fa9f6065ed669414996b447e2daf34b3495 100644
--- a/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java
+++ b/src/main/java/net/minecraft/world/level/block/entity/BlockEntity.java
@@ -26,6 +26,7 @@ import co.aikar.timings.MinecraftTimings; // Paper
 import co.aikar.timings.Timing; // Paper
 
 public abstract class BlockEntity {
+    static boolean ignoreTileUpdates; // Paper - Perf: Optimize Hoppers
 
     public Timing tickTimer = MinecraftTimings.getTileEntityTimings(this); // Paper
     // CraftBukkit start - data containers
@@ -161,6 +162,7 @@ public abstract class BlockEntity {
 
     public void setChanged() {
         if (this.level != null) {
+            if (ignoreTileUpdates) return; // Paper - Perf: Optimize Hoppers
             BlockEntity.setChanged(this.level, this.worldPosition, this.blockState);
         }
 
diff --git a/src/main/java/net/minecraft/world/level/block/entity/HopperBlockEntity.java b/src/main/java/net/minecraft/world/level/block/entity/HopperBlockEntity.java
index f98367830e87d5f1428448931f756d9277699563..df1c1c27b7c0065f8179d59bdb9de01dde22befa 100644
--- a/src/main/java/net/minecraft/world/level/block/entity/HopperBlockEntity.java
+++ b/src/main/java/net/minecraft/world/level/block/entity/HopperBlockEntity.java
@@ -151,6 +151,43 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
 
     }
 
+    // Paper start - Perf: Optimize Hoppers
+    private static final int HOPPER_EMPTY = 0;
+    private static final int HOPPER_HAS_ITEMS = 1;
+    private static final int HOPPER_IS_FULL = 2;
+
+    private static int getFullState(final HopperBlockEntity tileEntity) {
+        tileEntity.unpackLootTable(null);
+
+        final List<ItemStack> hopperItems = tileEntity.getItems();
+
+        boolean empty = true;
+        boolean full = true;
+
+        for (int i = 0, len = hopperItems.size(); i < len; ++i) {
+            final ItemStack stack = hopperItems.get(i);
+            if (stack.isEmpty()) {
+                full = false;
+                continue;
+            }
+
+            if (!full) {
+                // can't be full
+                return HOPPER_HAS_ITEMS;
+            }
+
+            empty = false;
+
+            if (stack.getCount() != stack.getMaxStackSize()) {
+                // can't be full or empty
+                return HOPPER_HAS_ITEMS;
+            }
+        }
+
+        return empty ? HOPPER_EMPTY : (full ? HOPPER_IS_FULL : HOPPER_HAS_ITEMS);
+    }
+    // Paper end - Perf: Optimize Hoppers
+
     private static boolean tryMoveItems(Level world, BlockPos pos, BlockState state, HopperBlockEntity blockEntity, BooleanSupplier booleansupplier) {
         if (world.isClientSide) {
             return false;
@@ -158,11 +195,13 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
             if (!blockEntity.isOnCooldown() && (Boolean) state.getValue(HopperBlock.ENABLED)) {
                 boolean flag = false;
 
-                if (!blockEntity.isEmpty()) {
+                int fullState = getFullState(blockEntity); // Paper - Perf: Optimize Hoppers
+
+                if (fullState != HOPPER_EMPTY) { // Paper - Perf: Optimize Hopperss
                     flag = HopperBlockEntity.ejectItems(world, pos, state, (Container) blockEntity, blockEntity); // CraftBukkit
                 }
 
-                if (!blockEntity.inventoryFull()) {
+                if (fullState != HOPPER_IS_FULL || flag) { // Paper - Perf: Optimize Hoppers
                     flag |= booleansupplier.getAsBoolean();
                 }
 
@@ -193,6 +232,202 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
         return false;
     }
 
+    // Paper start - Perf: Optimize Hoppers
+    private static boolean skipPullModeEventFire;
+    private static boolean skipPushModeEventFire;
+    public static boolean skipHopperEvents;
+
+    private static boolean hopperPush(final Level level, final Container destination, final Direction direction, final HopperBlockEntity hopper) {
+        skipPushModeEventFire = skipHopperEvents;
+        boolean foundItem = false;
+        for (int i = 0; i < hopper.getContainerSize(); ++i) {
+            final ItemStack item = hopper.getItem(i);
+            if (!item.isEmpty()) {
+                foundItem = true;
+                ItemStack origItemStack = item;
+                ItemStack movedItem = origItemStack;
+
+                final int originalItemCount = origItemStack.getCount();
+                final int movedItemCount = Math.min(level.spigotConfig.hopperAmount, originalItemCount);
+                origItemStack.setCount(movedItemCount);
+
+                // We only need to fire the event once to give protection plugins a chance to cancel this event
+                // Because nothing uses getItem, every event call should end up the same result.
+                if (!skipPushModeEventFire) {
+                    movedItem = callPushMoveEvent(destination, movedItem, hopper);
+                    if (movedItem == null) { // cancelled
+                        origItemStack.setCount(originalItemCount);
+                        return false;
+                    }
+                }
+
+                final ItemStack remainingItem = addItem(hopper, destination, movedItem, direction);
+                final int remainingItemCount = remainingItem.getCount();
+                if (remainingItemCount != movedItemCount) {
+                    origItemStack = origItemStack.copy(true);
+                    origItemStack.setCount(originalItemCount);
+                    if (!origItemStack.isEmpty()) {
+                        origItemStack.setCount(originalItemCount - movedItemCount + remainingItemCount);
+                    }
+                    hopper.setItem(i, origItemStack);
+                    destination.setChanged();
+                    return true;
+                }
+                origItemStack.setCount(originalItemCount);
+            }
+        }
+        if (foundItem && level.paperConfig().hopper.cooldownWhenFull) { // Inventory was full - cooldown
+            hopper.setCooldown(level.spigotConfig.hopperTransfer);
+        }
+        return false;
+    }
+
+    private static boolean hopperPull(final Level level, final Hopper hopper, final Container container, ItemStack origItemStack, final int i) {
+        ItemStack movedItem = origItemStack;
+        final int originalItemCount = origItemStack.getCount();
+        final int movedItemCount = Math.min(level.spigotConfig.hopperAmount, originalItemCount);
+        container.setChanged(); // original logic always marks source inv as changed even if no move happens.
+        movedItem.setCount(movedItemCount);
+
+        if (!skipPullModeEventFire) {
+            movedItem = callPullMoveEvent(hopper, container, movedItem);
+            if (movedItem == null) { // cancelled
+                origItemStack.setCount(originalItemCount);
+                // Drastically improve performance by returning true.
+                // No plugin could of relied on the behavior of false as the other call
+                // site for IMIE did not exhibit the same behavior
+                return true;
+            }
+        }
+
+        final ItemStack remainingItem = addItem(container, hopper, movedItem, null);
+        final int remainingItemCount = remainingItem.getCount();
+        if (remainingItemCount != movedItemCount) {
+            origItemStack = origItemStack.copy(true);
+            origItemStack.setCount(originalItemCount);
+            if (!origItemStack.isEmpty()) {
+                origItemStack.setCount(originalItemCount - movedItemCount + remainingItemCount);
+            }
+
+            ignoreTileUpdates = true;
+            container.setItem(i, origItemStack);
+            ignoreTileUpdates = false;
+            container.setChanged();
+            return true;
+        }
+        origItemStack.setCount(originalItemCount);
+
+        if (level.paperConfig().hopper.cooldownWhenFull) {
+            cooldownHopper(hopper);
+        }
+
+        return false;
+    }
+
+    @Nullable
+    private static ItemStack callPushMoveEvent(Container iinventory, ItemStack itemstack, HopperBlockEntity hopper) {
+        final Inventory destinationInventory = getInventory(iinventory);
+        final io.papermc.paper.event.inventory.PaperInventoryMoveItemEvent event = new io.papermc.paper.event.inventory.PaperInventoryMoveItemEvent(hopper.getOwner(false).getInventory(),
+            CraftItemStack.asCraftMirror(itemstack), destinationInventory, true);
+        final boolean result = event.callEvent();
+        if (!event.calledGetItem && !event.calledSetItem) {
+            skipPushModeEventFire = true;
+        }
+        if (!result) {
+            cooldownHopper(hopper);
+            return null;
+        }
+
+        if (event.calledSetItem) {
+            return CraftItemStack.asNMSCopy(event.getItem());
+        } else {
+            return itemstack;
+        }
+    }
+
+    @Nullable
+    private static ItemStack callPullMoveEvent(final Hopper hopper, final Container container, final ItemStack itemstack) {
+        final Inventory sourceInventory = getInventory(container);
+        final Inventory destination = getInventory(hopper);
+
+        // Mirror is safe as no plugins ever use this item
+        final io.papermc.paper.event.inventory.PaperInventoryMoveItemEvent event = new io.papermc.paper.event.inventory.PaperInventoryMoveItemEvent(sourceInventory, CraftItemStack.asCraftMirror(itemstack), destination, false);
+        final boolean result = event.callEvent();
+        if (!event.calledGetItem && !event.calledSetItem) {
+            skipPullModeEventFire = true;
+        }
+        if (!result) {
+            cooldownHopper(hopper);
+            return null;
+        }
+
+        if (event.calledSetItem) {
+            return CraftItemStack.asNMSCopy(event.getItem());
+        } else {
+            return itemstack;
+        }
+    }
+
+    private static Inventory getInventory(final Container container) {
+        final Inventory sourceInventory;
+        if (container instanceof CompoundContainer compoundContainer) {
+            // Have to special-case large chests as they work oddly
+            sourceInventory = new org.bukkit.craftbukkit.inventory.CraftInventoryDoubleChest(compoundContainer);
+        } else if (container instanceof BlockEntity blockEntity) {
+            sourceInventory = blockEntity.getOwner(false).getInventory();
+        } else if (container.getOwner() != null) {
+            sourceInventory = container.getOwner().getInventory();
+        } else {
+            sourceInventory = new CraftInventory(container);
+        }
+        return sourceInventory;
+    }
+
+    private static void cooldownHopper(final Hopper hopper) {
+        if (hopper instanceof HopperBlockEntity blockEntity && blockEntity.getLevel() != null) {
+            blockEntity.setCooldown(blockEntity.getLevel().spigotConfig.hopperTransfer);
+        }
+    }
+
+    private static boolean allMatch(Container iinventory, Direction enumdirection, java.util.function.BiPredicate<ItemStack, Integer> test) {
+        if (iinventory instanceof WorldlyContainer) {
+            for (int i : ((WorldlyContainer) iinventory).getSlotsForFace(enumdirection)) {
+                if (!test.test(iinventory.getItem(i), i)) {
+                    return false;
+                }
+            }
+        } else {
+            int size = iinventory.getContainerSize();
+            for (int i = 0; i < size; i++) {
+                if (!test.test(iinventory.getItem(i), i)) {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
+
+    private static boolean anyMatch(Container iinventory, Direction enumdirection, java.util.function.BiPredicate<ItemStack, Integer> test) {
+        if (iinventory instanceof WorldlyContainer) {
+            for (int i : ((WorldlyContainer) iinventory).getSlotsForFace(enumdirection)) {
+                if (test.test(iinventory.getItem(i), i)) {
+                    return true;
+                }
+            }
+        } else {
+            int size = iinventory.getContainerSize();
+            for (int i = 0; i < size; i++) {
+                if (test.test(iinventory.getItem(i), i)) {
+                    return true;
+                }
+            }
+        }
+        return true;
+    }
+    private static final java.util.function.BiPredicate<ItemStack, Integer> STACK_SIZE_TEST = (itemstack, i) -> itemstack.getCount() >= itemstack.getMaxStackSize();
+    private static final java.util.function.BiPredicate<ItemStack, Integer> IS_EMPTY_TEST = (itemstack, i) -> itemstack.isEmpty();
+    // Paper end - Perf: Optimize Hoppers
+
     private static boolean ejectItems(Level world, BlockPos blockposition, BlockState iblockdata, Container iinventory, HopperBlockEntity hopper) { // CraftBukkit
         Container iinventory1 = HopperBlockEntity.getAttachedContainer(world, blockposition, iblockdata);
 
@@ -204,46 +439,49 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
             if (HopperBlockEntity.isFullContainer(iinventory1, enumdirection)) {
                 return false;
             } else {
-                for (int i = 0; i < iinventory.getContainerSize(); ++i) {
-                    if (!iinventory.getItem(i).isEmpty()) {
-                        ItemStack itemstack = iinventory.getItem(i).copy();
-                        // ItemStack itemstack1 = addItem(iinventory, iinventory1, iinventory.removeItem(i, 1), enumdirection);
-
-                        // CraftBukkit start - Call event when pushing items into other inventories
-                        CraftItemStack oitemstack = CraftItemStack.asCraftMirror(iinventory.removeItem(i, world.spigotConfig.hopperAmount)); // Spigot
-
-                        Inventory destinationInventory;
-                        // Have to special case large chests as they work oddly
-                        if (iinventory1 instanceof CompoundContainer) {
-                            destinationInventory = new org.bukkit.craftbukkit.inventory.CraftInventoryDoubleChest((CompoundContainer) iinventory1);
-                        } else if (iinventory1.getOwner() != null) {
-                            destinationInventory = iinventory1.getOwner().getInventory();
-                        } else {
-                            destinationInventory = new CraftInventory(iinventory);
-                        }
-
-                        InventoryMoveItemEvent event = new InventoryMoveItemEvent(iinventory.getOwner().getInventory(), oitemstack.clone(), destinationInventory, true);
-                        world.getCraftServer().getPluginManager().callEvent(event);
-                        if (event.isCancelled()) {
-                            hopper.setItem(i, itemstack);
-                            hopper.setCooldown(world.spigotConfig.hopperTransfer); // Spigot
-                            return false;
-                        }
-                        int origCount = event.getItem().getAmount(); // Spigot
-                        ItemStack itemstack1 = HopperBlockEntity.addItem(iinventory, iinventory1, CraftItemStack.asNMSCopy(event.getItem()), enumdirection);
+                // Paper start - replace logic; MAKE SURE TO CHECK FOR DIFFS ON UPDATES
+                return hopperPush(world, iinventory1, enumdirection, hopper);
+                // for (int i = 0; i < iinventory.getContainerSize(); ++i) {
+                //     if (!iinventory.getItem(i).isEmpty()) {
+                //         ItemStack itemstack = iinventory.getItem(i).copy();
+                //         // ItemStack itemstack1 = addItem(iinventory, iinventory1, iinventory.removeItem(i, 1), enumdirection);
+
+                //         // CraftBukkit start - Call event when pushing items into other inventories
+                //         CraftItemStack oitemstack = CraftItemStack.asCraftMirror(iinventory.removeItem(i, world.spigotConfig.hopperAmount)); // Spigot
+
+                //         Inventory destinationInventory;
+                //        // Have to special case large chests as they work oddly
+                //         if (iinventory1 instanceof CompoundContainer) {
+                //             destinationInventory = new org.bukkit.craftbukkit.inventory.CraftInventoryDoubleChest((CompoundContainer) iinventory1);
+                //         } else if (iinventory1.getOwner() != null) {
+                //             destinationInventory = iinventory1.getOwner().getInventory();
+                //         } else {
+                //             destinationInventory = new CraftInventory(iinventory);
+                //         }
+
+                //         InventoryMoveItemEvent event = new InventoryMoveItemEvent(iinventory.getOwner().getInventory(), oitemstack.clone(), destinationInventory, true);
+                //         world.getCraftServer().getPluginManager().callEvent(event);
+                //         if (event.isCancelled()) {
+                //             hopper.setItem(i, itemstack);
+                //             hopper.setCooldown(world.spigotConfig.hopperTransfer); // Spigot
+                //             return false;
+                //         }
+                //         int origCount = event.getItem().getAmount(); // Spigot
+                //         ItemStack itemstack1 = HopperBlockEntity.addItem(iinventory, iinventory1, CraftItemStack.asNMSCopy(event.getItem()), enumdirection);
                         // CraftBukkit end
 
-                        if (itemstack1.isEmpty()) {
-                            iinventory1.setChanged();
-                            return true;
-                        }
+                //         if (itemstack1.isEmpty()) {
+                //             iinventory1.setChanged();
+                //             return true;
+                //         }
 
-                        itemstack.shrink(origCount - itemstack1.getCount()); // Spigot
-                        iinventory.setItem(i, itemstack);
-                    }
-                }
+                //         itemstack.shrink(origCount - itemstack1.getCount()); // Spigot
+                //         iinventory.setItem(i, itemstack);
+                //     }
+                // }
 
-                return false;
+                // return false;
+                // Paper end - Perf: Optimize Hoppers
             }
         }
     }
@@ -253,17 +491,29 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
     }
 
     private static boolean isFullContainer(Container inventory, Direction direction) {
-        return HopperBlockEntity.getSlots(inventory, direction).allMatch((i) -> {
-            ItemStack itemstack = inventory.getItem(i);
-
-            return itemstack.getCount() >= itemstack.getMaxStackSize();
-        });
+        // Paper start - Perf: Optimize Hoppers
+        if (inventory instanceof WorldlyContainer worldlyContainer) {
+            for (final int slot : worldlyContainer.getSlotsForFace(direction)) {
+                final ItemStack stack = inventory.getItem(slot);
+                if (stack.getCount() < stack.getMaxStackSize()) {
+                    return false;
+                }
+            }
+            return true;
+        } else {
+            for (int slot = 0, max = inventory.getContainerSize(); slot < max; ++slot) {
+                final ItemStack stack = inventory.getItem(slot);
+                if (stack.getCount() < stack.getMaxStackSize()) {
+                    return false;
+                }
+            }
+            return true;
+        }
+        // Paper end - Perf: Optimize Hoppers
     }
 
     private static boolean isEmptyContainer(Container inv, Direction facing) {
-        return HopperBlockEntity.getSlots(inv, facing).allMatch((i) -> {
-            return inv.getItem(i).isEmpty();
-        });
+        return allMatch(inv, facing, IS_EMPTY_TEST); // Paper - Perf: Optimize Hoppers
     }
 
     public static boolean suckInItems(Level world, Hopper hopper) {
@@ -272,9 +522,33 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
         if (iinventory != null) {
             Direction enumdirection = Direction.DOWN;
 
-            return HopperBlockEntity.isEmptyContainer(iinventory, enumdirection) ? false : HopperBlockEntity.getSlots(iinventory, enumdirection).anyMatch((i) -> {
-                return HopperBlockEntity.a(hopper, iinventory, i, enumdirection, world); // Spigot
-            });
+            // Paper start - Perf: Optimize Hoppers
+            skipPullModeEventFire = skipHopperEvents;
+            // merge container isEmpty check and move logic into one loop
+            if (iinventory instanceof WorldlyContainer worldlyContainer) {
+                for (final int slot : worldlyContainer.getSlotsForFace(enumdirection)) {
+                    ItemStack item = worldlyContainer.getItem(slot);
+                    if (item.isEmpty() || !canTakeItemFromContainer(hopper, iinventory, item, slot, enumdirection)) {
+                        continue;
+                    }
+                    if (hopperPull(world, hopper, iinventory, item, slot)) {
+                        return true;
+                    }
+                }
+                return false;
+            } else {
+                for (int slot = 0, max = iinventory.getContainerSize(); slot < max; ++slot) {
+                    ItemStack item = iinventory.getItem(slot);
+                    if (item.isEmpty() || !canTakeItemFromContainer(hopper, iinventory, item, slot, enumdirection)) {
+                        continue;
+                    }
+                    if (hopperPull(world, hopper, iinventory, item, slot)) {
+                        return true;
+                    }
+                }
+                return false;
+            }
+            // Paper end - Perf: Optimize Hoppers
         } else {
             Iterator iterator = HopperBlockEntity.getItemsAtAndAbove(world, hopper).iterator();
 
@@ -292,48 +566,52 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
         }
     }
 
+    @io.papermc.paper.annotation.DoNotUse // Paper - method unused as logic is inlined above
     private static boolean a(Hopper ihopper, Container iinventory, int i, Direction enumdirection, Level world) { // Spigot
         ItemStack itemstack = iinventory.getItem(i);
 
-        if (!itemstack.isEmpty() && HopperBlockEntity.canTakeItemFromContainer(ihopper, iinventory, itemstack, i, enumdirection)) {
-            ItemStack itemstack1 = itemstack.copy();
-            // ItemStack itemstack2 = addItem(iinventory, ihopper, iinventory.removeItem(i, 1), (EnumDirection) null);
-            // CraftBukkit start - Call event on collection of items from inventories into the hopper
-            CraftItemStack oitemstack = CraftItemStack.asCraftMirror(iinventory.removeItem(i, world.spigotConfig.hopperAmount)); // Spigot
-
-            Inventory sourceInventory;
-            // Have to special case large chests as they work oddly
-            if (iinventory instanceof CompoundContainer) {
-                sourceInventory = new org.bukkit.craftbukkit.inventory.CraftInventoryDoubleChest((CompoundContainer) iinventory);
-            } else if (iinventory.getOwner() != null) {
-                sourceInventory = iinventory.getOwner().getInventory();
-            } else {
-                sourceInventory = new CraftInventory(iinventory);
-            }
-
-            InventoryMoveItemEvent event = new InventoryMoveItemEvent(sourceInventory, oitemstack.clone(), ihopper.getOwner().getInventory(), false);
-
-            Bukkit.getServer().getPluginManager().callEvent(event);
-            if (event.isCancelled()) {
-                iinventory.setItem(i, itemstack1);
-
-                if (ihopper instanceof HopperBlockEntity) {
-                    ((HopperBlockEntity) ihopper).setCooldown(world.spigotConfig.hopperTransfer); // Spigot
-                }
-
-                return false;
-            }
-            int origCount = event.getItem().getAmount(); // Spigot
-            ItemStack itemstack2 = HopperBlockEntity.addItem(iinventory, ihopper, CraftItemStack.asNMSCopy(event.getItem()), null);
-            // CraftBukkit end
-
-            if (itemstack2.isEmpty()) {
-                iinventory.setChanged();
-                return true;
-            }
-
-            itemstack1.shrink(origCount - itemstack2.getCount()); // Spigot
-            iinventory.setItem(i, itemstack1);
+        // Paper start - Perf: Optimize Hoppers; replace pull logic; MAKE SURE TO CHECK FOR DIFFS WHEN UPDATING
+        if (!itemstack.isEmpty() && HopperBlockEntity.canTakeItemFromContainer(ihopper, iinventory, itemstack, i, enumdirection)) { // If this logic changes, update above. this is left unused incase reflective plugins
+            return hopperPull(world, ihopper, iinventory, itemstack, i);
+            // ItemStack itemstack1 = itemstack.copy();
+            // // ItemStack itemstack2 = addItem(iinventory, ihopper, iinventory.removeItem(i, 1), (EnumDirection) null);
+            // // CraftBukkit start - Call event on collection of items from inventories into the hopper
+            // CraftItemStack oitemstack = CraftItemStack.asCraftMirror(iinventory.removeItem(i, world.spigotConfig.hopperAmount)); // Spigot
+
+            // Inventory sourceInventory;
+            // // Have to special case large chests as they work oddly
+            // if (iinventory instanceof CompoundContainer) {
+            //     sourceInventory = new org.bukkit.craftbukkit.inventory.CraftInventoryDoubleChest((CompoundContainer) iinventory);
+            // } else if (iinventory.getOwner() != null) {
+            //     sourceInventory = iinventory.getOwner().getInventory();
+            // } else {
+            //     sourceInventory = new CraftInventory(iinventory);
+            // }
+
+            // InventoryMoveItemEvent event = new InventoryMoveItemEvent(sourceInventory, oitemstack.clone(), ihopper.getOwner().getInventory(), false);
+
+            // Bukkit.getServer().getPluginManager().callEvent(event);
+            // if (event.isCancelled()) {
+            //     iinventory.setItem(i, itemstack1);
+
+                // if (ihopper instanceof HopperBlockEntity) {
+                //     ((HopperBlockEntity) ihopper).setCooldown(world.spigotConfig.hopperTransfer); // Spigot
+                // }
+
+                // return false;
+            // }
+            // int origCount = event.getItem().getAmount(); // Spigot
+            // ItemStack itemstack2 = HopperBlockEntity.addItem(iinventory, ihopper, CraftItemStack.asNMSCopy(event.getItem()), null);
+            // // CraftBukkit end
+
+            // if (itemstack2.isEmpty()) {
+            //     iinventory.setChanged();
+            //     return true;
+            // }
+
+            // itemstack1.shrink(origCount - itemstack2.getCount()); // Spigot
+            // iinventory.setItem(i, itemstack1);
+            // Paper end - Perf: Optimize Hoppers
         }
 
         return false;
@@ -342,12 +620,14 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
     public static boolean addItem(Container inventory, ItemEntity itemEntity) {
         boolean flag = false;
         // CraftBukkit start
-        InventoryPickupItemEvent event = new InventoryPickupItemEvent(inventory.getOwner().getInventory(), (org.bukkit.entity.Item) itemEntity.getBukkitEntity());
+        if (InventoryPickupItemEvent.getHandlerList().getRegisteredListeners().length > 0) { // Paper - optimize hoppers
+        InventoryPickupItemEvent event = new InventoryPickupItemEvent(getInventory(inventory), (org.bukkit.entity.Item) itemEntity.getBukkitEntity()); // Paper - Perf: Optimize Hoppers; use getInventory() to avoid snapshot creation
         itemEntity.level().getCraftServer().getPluginManager().callEvent(event);
         if (event.isCancelled()) {
             return false;
         }
         // CraftBukkit end
+        } // Paper - Perf: Optimize Hoppers
         ItemStack itemstack = itemEntity.getItem().copy();
         ItemStack itemstack1 = HopperBlockEntity.addItem((Container) null, inventory, itemstack, (Direction) null);
 
@@ -443,7 +723,9 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
                     stack = stack.split(to.getMaxStackSize());
                 }
                 // Spigot end
+                ignoreTileUpdates = true; // Paper - Perf: Optimize Hoppers
                 to.setItem(slot, stack);
+                ignoreTileUpdates = false; // Paper - Perf: Optimize Hoppers
                 stack = leftover; // Paper
                 flag = true;
             } else if (HopperBlockEntity.canMergeItems(itemstack1, stack)) {
@@ -517,19 +799,47 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
         // CraftBukkit end
     }
 
+    // Paper start - Perf: Optimize Hoppers
+    static final AABB HOPPER_ITEM_SUCK_OVERALL = Hopper.SUCK.bounds();
+    static final AABB[] HOPPER_ITEM_SUCK_INDIVIDUAL = Hopper.SUCK.toAabbs().toArray(new AABB[0]);
+    // Paper end - Perf: Optimize Hoppers
+
     public static List<ItemEntity> getItemsAtAndAbove(Level world, Hopper hopper) {
-        return (List) hopper.getSuckShape().toAabbs().stream().flatMap((axisalignedbb) -> {
-            return world.getEntitiesOfClass(ItemEntity.class, axisalignedbb.move(hopper.getLevelX() - 0.5D, hopper.getLevelY() - 0.5D, hopper.getLevelZ() - 0.5D), EntitySelector.ENTITY_STILL_ALIVE).stream();
-        }).collect(Collectors.toList());
+        // Paper start - Perf: Optimize Hoppers
+        // eliminate multiple getEntitiesOfClass() but maintain the voxelshape collision by moving
+        // the individual AABB checks into the predicate
+        final double shiftX = hopper.getLevelX() - 0.5D;
+        final double shiftY = hopper.getLevelY() - 0.5D;
+        final double shiftZ = hopper.getLevelZ() - 0.5D;
+        return world.getEntitiesOfClass(ItemEntity.class, HOPPER_ITEM_SUCK_OVERALL.move(shiftX, shiftY, shiftZ), (final Entity entity) -> {
+            if (!entity.isAlive()) { // EntitySelector.ENTITY_STILL_ALIVE
+                return false;
+            }
+
+            for (final AABB aabb : HOPPER_ITEM_SUCK_INDIVIDUAL) {
+                if (aabb.move(shiftX, shiftY, shiftZ).intersects(entity.getBoundingBox())) {
+                    return true;
+                }
+            }
+
+            return false;
+        });
+        // Paper end - Perf: Optimize Hoppers
     }
 
     @Nullable
     public static Container getContainerAt(Level world, BlockPos pos) {
-        return HopperBlockEntity.getContainerAt(world, (double) pos.getX() + 0.5D, (double) pos.getY() + 0.5D, (double) pos.getZ() + 0.5D);
+        return HopperBlockEntity.getContainerAt(world, (double) pos.getX() + 0.5D, (double) pos.getY() + 0.5D, (double) pos.getZ() + 0.5D, true); // Paper - Perf: Optimize Hoppers
     }
 
     @Nullable
     private static Container getContainerAt(Level world, double x, double y, double z) {
+        // Paper start - Perf: Optimize Hoppers
+        return HopperBlockEntity.getContainerAt(world, x, y, z, false);
+    }
+    @Nullable
+    private static Container getContainerAt(Level world, double x, double y, double z, final boolean optimizeEntities) {
+        // Paper end - Perf: Optimize Hoppers
         Object object = null;
         BlockPos blockposition = BlockPos.containing(x, y, z);
         if ( !world.spigotConfig.hopperCanLoadChunks && !world.hasChunkAt( blockposition ) ) return null; // Spigot
@@ -549,8 +859,8 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
             }
         }
 
-        if (object == null) {
-            List<Entity> list = world.getEntities((Entity) null, new AABB(x - 0.5D, y - 0.5D, z - 0.5D, x + 0.5D, y + 0.5D, z + 0.5D), EntitySelector.CONTAINER_ENTITY_SELECTOR);
+        if (object == null && (!optimizeEntities || !world.paperConfig().hopper.ignoreOccludingBlocks || !iblockdata.getBukkitMaterial().isOccluding())) { // Paper - Perf: Optimize Hoppers
+            List<Entity> list = world.getEntitiesOfClass((Class)Container.class, new AABB(x - 0.5D, y - 0.5D, z - 0.5D, x + 0.5D, y + 0.5D, z + 0.5D), EntitySelector.CONTAINER_ENTITY_SELECTOR); // Paper - Perf: Optimize Hoppers
 
             if (!list.isEmpty()) {
                 object = (Container) list.get(world.random.nextInt(list.size()));
@@ -561,7 +871,7 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
     }
 
     private static boolean canMergeItems(ItemStack first, ItemStack second) {
-        return first.getCount() <= first.getMaxStackSize() && ItemStack.isSameItemSameTags(first, second);
+        return first.getCount() < first.getMaxStackSize() && first.is(second.getItem()) && first.getDamageValue() == second.getDamageValue() && ((first.isEmpty() && second.isEmpty()) || java.util.Objects.equals(first.getTag(), second.getTag())); // Paper - Perf: Optimize Hoppers; used to return true for full itemstacks?!
     }
 
     @Override
diff --git a/src/main/java/net/minecraft/world/level/block/entity/RandomizableContainerBlockEntity.java b/src/main/java/net/minecraft/world/level/block/entity/RandomizableContainerBlockEntity.java
index 7cbd403f9e96e7ce35475c8102cd9f9c04819c27..a94300a457b25f0e33a8eeabba6dd5720ca9ab1e 100644
--- a/src/main/java/net/minecraft/world/level/block/entity/RandomizableContainerBlockEntity.java
+++ b/src/main/java/net/minecraft/world/level/block/entity/RandomizableContainerBlockEntity.java
@@ -93,12 +93,19 @@ public abstract class RandomizableContainerBlockEntity extends BaseContainerBloc
     @Override
     public boolean isEmpty() {
         this.unpackLootTable((Player)null);
-        return this.getItems().stream().allMatch(ItemStack::isEmpty);
+        // Paper start - Perf: Optimize Hoppers
+        for (final ItemStack itemStack : this.getItems()) {
+            if (!itemStack.isEmpty()) {
+                return false;
+            }
+        }
+        return true;
+        // Paper end - Perf: Optimize Hoppers
     }
 
     @Override
     public ItemStack getItem(int slot) {
-        this.unpackLootTable((Player)null);
+        if (slot == 0) this.unpackLootTable((Player) null); // Paper - Perf: Optimize Hoppers
         return this.getItems().get(slot);
     }