PaperMC/patches/server/0963-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
* 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/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index fbc06f45926e9073c95c97423f92a213898fcd48..9f15d9dbdfa74a0640b1a2b4ff695609d4758a4c 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -1525,6 +1525,7 @@ 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 ce51f1768275fab434d46b5aa349dfdd2b631977..1aac66a8ef170f172b7cf4045d77800f93e26d3a 100644
--- a/src/main/java/net/minecraft/world/item/ItemStack.java
+++ b/src/main/java/net/minecraft/world/item/ItemStack.java
@@ -710,10 +710,16 @@ 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 585d1d1f4b1b212295da36e31ae2670b0d2b06c3..1b248db497500aa6bd346b306dcb908af77626f3 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
@@ -162,6 +163,7 @@ 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 789e5458f4a137694563a22612455506807de51b..aac5572c1d40a10cd1d17f89c9eb836718837577 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
@@ -193,6 +193,201 @@ 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);
+        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 InventoryMoveItemEvent event = new InventoryMoveItemEvent(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 InventoryMoveItemEvent event = new InventoryMoveItemEvent(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 +399,49 @@ 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 +451,11 @@ 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();
-        });
+        return allMatch(inventory, direction, STACK_SIZE_TEST); // Paper - no streams
     }
 
     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) {
@@ -272,8 +464,16 @@ 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;
+            return !HopperBlockEntity.isEmptyContainer(iinventory, enumdirection) && anyMatch(iinventory, enumdirection, (item, i) -> {
+                // Logic copied from below to avoid extra getItem calls
+                if (!item.isEmpty() && canTakeItemFromContainer(hopper, iinventory, item, i, enumdirection)) {
+                    return hopperPull(world, hopper, iinventory, item, i);
+                } else {
+                    return false;
+                }
+                // Paper end
             });
         } else {
             Iterator iterator = HopperBlockEntity.getItemsAtAndAbove(world, hopper).iterator();
@@ -292,48 +492,52 @@ 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;
@@ -342,7 +546,7 @@ 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());
+        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;
@@ -442,7 +646,9 @@ 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)) {
@@ -517,18 +723,28 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
     }
 
     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 item suck in. remove streams, restore 1.12 checks. Seriously checking the bowl?!
+        double x = hopper.getLevelX();
+        double y = hopper.getLevelY();
+        double z = hopper.getLevelZ();
+        AABB bb = new AABB(x - 0.5D, y, z - 0.5D, x + 0.5D, y + 1.5D, z + 0.5D);
+        return world.getEntitiesOfClass(ItemEntity.class, bb, Entity::isAlive);
+        // Paper end
     }
 
     @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
@@ -548,7 +764,7 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
             }
         }
 
-        if (object == null) {
+        if (object == null && (!optimizeEntities || !world.paperConfig().hopper.ignoreOccludingBlocks || !org.bukkit.craftbukkit.util.CraftMagicNumbers.getMaterial(block).isOccluding())) { // Paper
             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 (!list.isEmpty()) {
@@ -560,7 +776,7 @@ public class HopperBlockEntity extends RandomizableContainerBlockEntity implemen
     }
 
     private static boolean canMergeItems(ItemStack first, ItemStack second) {
-        return !first.is(second.getItem()) ? false : (first.getDamageValue() != second.getDamageValue() ? false : (first.getCount() > first.getMaxStackSize() ? false : ItemStack.tagMatches(first, second)));
+        return first.is(second.getItem()) && first.getDamageValue() == second.getDamageValue() && first.getCount() < first.getMaxStackSize() && ItemStack.tagMatches(first, second); // 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 b9f0dae1ec96194fe78c086b63d8a18b1d0cfcf7..79b01e32f89defb6b78f4764600d33d4945af592 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
@@ -96,12 +96,19 @@ 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);
     }