Paper/patches/server/0918-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 a2961f1453e3805879941c709ab74a608285db42..50316da08ae259dcc0d02c28081a352f09d1a19a 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -1678,6 +1678,7 @@ 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
             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 3904c9d3ffde11320306f7c5c01ec2b8b0dfbaf9..26d00500831d07f2ef48da89770b3ece2cdc846b 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
+        return this.copy(false);
+    }
+
+    public ItemStack copy(boolean originalItem) {
+        if (!originalItem && this.isEmpty()) {
+            // Paper end
             return ItemStack.EMPTY;
         } else {
-            ItemStack itemstack = new ItemStack(this.getItem(), this.count);
+            ItemStack itemstack = new ItemStack(originalItem ? this.item : this.getItem(), this.count); // Paper
 
             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..370a25d2deb54f10a35ee24d9e7e92fbfde60edf 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
 
     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
             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..d4dcf7fe26474ae07374e7761d823bc5c8b54f97 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 - 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 - 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 - optimize hoppers
+
+                if (fullState != HOPPER_EMPTY) { // Paper - optimize hoppers
                     flag = HopperBlockEntity.ejectItems(world, pos, state, (Container) blockEntity, blockEntity); // CraftBukkit
                 }
 
-                if (!blockEntity.inventoryFull()) {
+                if (fullState != HOPPER_IS_FULL || flag) { // Paper - optimize hoppers
                     flag |= booleansupplier.getAsBoolean();
                 }
 
@@ -193,6 +232,202 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
         return false;
     }
 
+    // Paper start - 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
+
     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
             }
         }
     }
@@ -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 - 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 - 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);
     }
 
     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 - optimize hoppers and remove streams
+            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
         } 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 - 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
         }
 
         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 - use getInventory() to avoid snapshot creation
         itemEntity.level().getCraftServer().getPluginManager().callEvent(event);
         if (event.isCancelled()) {
             return false;
         }
         // CraftBukkit end
+        } // Paper - 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
                 to.setItem(slot, stack);
+                ignoreTileUpdates = false; // Paper
                 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 - optimize hopper item suck in
+    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 - optimize hopper item suck in
+
     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 - optimize hopper item suck in
+        // 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 - optimize hopper item suck in
     }
 
     @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
     }
 
     @Nullable
     private static Container getContainerAt(Level world, double x, double y, double z) {
+        // Paper start - add optimizeEntities parameter
+        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 - add optimizeEntities parameter
         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
+            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 - optimize hoppers, use getEntitiesOfClass
 
             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 - 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 e1baba8135b5599d5f1c70024e313f4d2c9c9daf..471de07d47cf3f60cda4a7bcbb27a2fd1e8e3f73 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
@@ -103,12 +103,19 @@ public abstract class RandomizableContainerBlockEntity extends BaseContainerBloc
     @Override
     public boolean isEmpty() {
         this.unpackLootTable((Player)null);
-        return this.getItems().stream().allMatch(ItemStack::isEmpty);
+        // Paper start
+        for (final ItemStack itemStack : this.getItems()) {
+            if (!itemStack.isEmpty()) {
+                return false;
+            }
+        }
+        return true;
+        // Paper end
     }
 
     @Override
     public ItemStack getItem(int slot) {
-        this.unpackLootTable((Player)null);
+        if (slot == 0) this.unpackLootTable((Player)null); // Paper
         return this.getItems().get(slot);
     }