Paper/Spigot-Server-Patches/0393-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/com/destroystokyo/paper/PaperWorldConfig.java b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
index b94c8e33780e10e458951384ffc49bd7fb015a6b..d846c55de176879e94f6c0e5bf8f58910657fc75 100644
--- a/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
+++ b/src/main/java/com/destroystokyo/paper/PaperWorldConfig.java
@@ -571,4 +571,13 @@ public class PaperWorldConfig {
     private void entitiesTargetWithFollowRange() {
         entitiesTargetWithFollowRange = getBoolean("entities-target-with-follow-range", entitiesTargetWithFollowRange);
     }
+
+    public boolean cooldownHopperWhenFull = true;
+    public boolean disableHopperMoveEvents = false;
+    private void hopperOptimizations() {
+        cooldownHopperWhenFull = getBoolean("hopper.cooldown-when-full", cooldownHopperWhenFull);
+        log("Cooldown Hoppers when Full: " + (cooldownHopperWhenFull ? "enabled" : "disabled"));
+        disableHopperMoveEvents = getBoolean("hopper.disable-move-event", disableHopperMoveEvents);
+        log("Hopper Move Item Events: " + (disableHopperMoveEvents ? "disabled" : "enabled"));
+    }
 }
diff --git a/src/main/java/net/minecraft/server/IHopper.java b/src/main/java/net/minecraft/server/IHopper.java
index b548ab8b7eb7e3c8a455f4653c30ea1610f268e8..187000f1e49f6609267b00f69fe2d266ea6b9255 100644
--- a/src/main/java/net/minecraft/server/IHopper.java
+++ b/src/main/java/net/minecraft/server/IHopper.java
@@ -12,12 +12,13 @@ public interface IHopper extends IInventory {
         return IHopper.c;
     }
 
-    @Nullable
+    //@Nullable // Paper - it's annoying
     World getWorld();
+    default BlockPosition getBlockPosition() { return new BlockPosition(getX(), getY(), getZ()); } // Paper
 
-    double x();
+    double x(); default double getX() { return this.x(); } // Paper - OBFHELPER
 
-    double z();
+    double z(); default double getY() { return this.z(); } // Paper - OBFHELPER
 
-    double A();
+    double A(); default double getZ() { return this.A(); } // Paper - OBFHELPER
 }
diff --git a/src/main/java/net/minecraft/server/ItemStack.java b/src/main/java/net/minecraft/server/ItemStack.java
index 63aa474c73f506737cb5de31977bffcd17d4dc11..b6703378e21a6cd7e140fd35756a20d47f49ed31 100644
--- a/src/main/java/net/minecraft/server/ItemStack.java
+++ b/src/main/java/net/minecraft/server/ItemStack.java
@@ -486,11 +486,12 @@ public final class ItemStack {
         return this.getItem().a(this, entityhuman, entityliving, enumhand);
     }
 
-    public ItemStack cloneItemStack() {
-        if (this.isEmpty()) {
+    public ItemStack cloneItemStack() { return cloneItemStack(false); } // Paper
+    public ItemStack cloneItemStack(boolean origItem) { // Paper
+        if (!origItem && this.isEmpty()) { // Paper
             return ItemStack.b;
         } else {
-            ItemStack itemstack = new ItemStack(this.getItem(), this.count);
+            ItemStack itemstack = new ItemStack(origItem ? this.item : this.getItem(), this.count); // Paper
 
             itemstack.d(this.D());
             if (this.tag != null) {
diff --git a/src/main/java/net/minecraft/server/MinecraftServer.java b/src/main/java/net/minecraft/server/MinecraftServer.java
index b47b9d0acef5de86ff31a5db9bb82dd41b586e0b..b5c27dda45d5403aeabaa837645a8bb656c09eb3 100644
--- a/src/main/java/net/minecraft/server/MinecraftServer.java
+++ b/src/main/java/net/minecraft/server/MinecraftServer.java
@@ -1245,6 +1245,7 @@ public abstract class MinecraftServer extends IAsyncTaskHandlerReentrant<TickTas
         while (iterator.hasNext()) {
             WorldServer worldserver = (WorldServer) iterator.next();
             worldserver.hasPhysicsEvent =  org.bukkit.event.block.BlockPhysicsEvent.getHandlerList().getRegisteredListeners().length > 0; // Paper
+            TileEntityHopper.skipHopperEvents = worldserver.paperConfig.disableHopperMoveEvents || org.bukkit.event.inventory.InventoryMoveItemEvent.getHandlerList().getRegisteredListeners().length == 0; // Paper
 
             this.methodProfiler.a(() -> {
                 return worldserver + " " + worldserver.getDimensionKey().a();
diff --git a/src/main/java/net/minecraft/server/TileEntity.java b/src/main/java/net/minecraft/server/TileEntity.java
index 338cf8c896a6fc869eb9c54d39ad5713f6fcc377..d32540c88bb902e9c191142a2b75a05b63218e52 100644
--- a/src/main/java/net/minecraft/server/TileEntity.java
+++ b/src/main/java/net/minecraft/server/TileEntity.java
@@ -63,6 +63,7 @@ public abstract class TileEntity implements KeyedObject { // Paper
     public void setCurrentChunk(Chunk chunk) {
         this.currentChunk = chunk != null ? new java.lang.ref.WeakReference<>(chunk) : null;
     }
+    static boolean IGNORE_TILE_UPDATES = false;
     // Paper end
 
     @Nullable
@@ -141,6 +142,7 @@ public abstract class TileEntity implements KeyedObject { // Paper
 
     public void update() {
         if (this.world != null) {
+            if (IGNORE_TILE_UPDATES) return; // Paper
             this.c = this.world.getType(this.position);
             this.world.b(this.position, this);
             if (!this.c.isAir()) {
diff --git a/src/main/java/net/minecraft/server/TileEntityHopper.java b/src/main/java/net/minecraft/server/TileEntityHopper.java
index 4398f452c52182694c5e2c0945fe70ca32cb0dfd..d432de40eba2767f4ced4d9c642c9d2033acd0ea 100644
--- a/src/main/java/net/minecraft/server/TileEntityHopper.java
+++ b/src/main/java/net/minecraft/server/TileEntityHopper.java
@@ -168,6 +168,160 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
         return false;
     }
 
+    // Paper start - Optimize Hoppers
+    private static boolean skipPullModeEventFire = false;
+    private static boolean skipPushModeEventFire = false;
+    static boolean skipHopperEvents = false;
+
+    private boolean hopperPush(IInventory iinventory, EnumDirection enumdirection) {
+        skipPushModeEventFire = skipHopperEvents;
+        boolean foundItem = false;
+        for (int i = 0; i < this.getSize(); ++i) {
+            ItemStack item = this.getItem(i);
+            if (!item.isEmpty()) {
+                foundItem = true;
+                ItemStack origItemStack = item;
+                ItemStack itemstack = origItemStack;
+
+                final int origCount = origItemStack.getCount();
+                final int moved = Math.min(world.spigotConfig.hopperAmount, origCount);
+                origItemStack.setCount(moved);
+
+                // 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) {
+                    itemstack = callPushMoveEvent(iinventory, itemstack);
+                    if (itemstack == null) { // cancelled
+                        origItemStack.setCount(origCount);
+                        return false;
+                    }
+                }
+                final ItemStack itemstack2 = addItem(this, iinventory, itemstack, enumdirection);
+                final int remaining = itemstack2.getCount();
+                if (remaining != moved) {
+                    origItemStack = origItemStack.cloneItemStack(true);
+                    origItemStack.setCount(origCount);
+                    if (!origItemStack.isEmpty()) {
+                        origItemStack.setCount(origCount - moved + remaining);
+                    }
+                    this.setItem(i, origItemStack);
+                    iinventory.update();
+                    return true;
+                }
+                origItemStack.setCount(origCount);
+            }
+        }
+        if (foundItem && world.paperConfig.cooldownHopperWhenFull) { // Inventory was full - cooldown
+            this.setCooldown(world.spigotConfig.hopperTransfer);
+        }
+        return false;
+    }
+
+    private static boolean hopperPull(IHopper ihopper, IInventory iinventory, ItemStack origItemStack, int i) {
+        ItemStack itemstack = origItemStack;
+        final int origCount = origItemStack.getCount();
+        final World world = ihopper.getWorld();
+        final int moved = Math.min(world.spigotConfig.hopperAmount, origCount);
+        itemstack.setCount(moved);
+
+        if (!skipPullModeEventFire) {
+            itemstack = callPullMoveEvent(ihopper, iinventory, itemstack);
+            if (itemstack == null) { // cancelled
+                origItemStack.setCount(origCount);
+                // 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 itemstack2 = addItem(iinventory, ihopper, itemstack, null);
+        final int remaining = itemstack2.getCount();
+        if (remaining != moved) {
+            origItemStack = origItemStack.cloneItemStack(true);
+            origItemStack.setCount(origCount);
+            if (!origItemStack.isEmpty()) {
+                origItemStack.setCount(origCount - moved + remaining);
+            }
+            IGNORE_TILE_UPDATES = true;
+            iinventory.setItem(i, origItemStack);
+            IGNORE_TILE_UPDATES = false;
+            iinventory.update();
+            return true;
+        }
+        origItemStack.setCount(origCount);
+
+        if (world.paperConfig.cooldownHopperWhenFull) {
+            cooldownHopper(ihopper);
+        }
+
+        return false;
+    }
+
+    private ItemStack callPushMoveEvent(IInventory iinventory, ItemStack itemstack) {
+        Inventory destinationInventory = getInventory(iinventory);
+        InventoryMoveItemEvent event = new InventoryMoveItemEvent(this.getOwner(false).getInventory(),
+            CraftItemStack.asCraftMirror(itemstack), destinationInventory, true);
+        boolean result = event.callEvent();
+        if (!event.calledGetItem && !event.calledSetItem) {
+            skipPushModeEventFire = true;
+        }
+        if (!result) {
+            cooldownHopper(this);
+            return null;
+        }
+
+        if (event.calledSetItem) {
+            return CraftItemStack.asNMSCopy(event.getItem());
+        } else {
+            return itemstack;
+        }
+    }
+
+    private static ItemStack callPullMoveEvent(IHopper hopper, IInventory iinventory, ItemStack itemstack) {
+        Inventory sourceInventory = getInventory(iinventory);
+        Inventory destination = getInventory(hopper);
+
+        InventoryMoveItemEvent event = new InventoryMoveItemEvent(sourceInventory,
+            // Mirror is safe as we no plugins ever use this item
+            CraftItemStack.asCraftMirror(itemstack), destination, false);
+        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(IInventory iinventory) {
+        Inventory sourceInventory;// Have to special case large chests as they work oddly
+        if (iinventory instanceof InventoryLargeChest) {
+            sourceInventory = new org.bukkit.craftbukkit.inventory.CraftInventoryDoubleChest((InventoryLargeChest) iinventory);
+        } else if (iinventory instanceof TileEntity) {
+            sourceInventory = ((TileEntity) iinventory).getOwner(false).getInventory();
+        } else {
+            sourceInventory = iinventory.getOwner().getInventory();
+        }
+        return sourceInventory;
+    }
+
+    private static void cooldownHopper(IHopper hopper) {
+        if (hopper instanceof TileEntityHopper) {
+            ((TileEntityHopper) hopper).setCooldown(hopper.getWorld().spigotConfig.hopperTransfer);
+        } else if (hopper instanceof EntityMinecartHopper) {
+            ((EntityMinecartHopper) hopper).setCooldown(hopper.getWorld().spigotConfig.hopperTransfer / 2);
+        }
+    }
+    // Paper end
+
     private boolean k() {
         IInventory iinventory = this.l();
 
@@ -179,6 +333,7 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
             if (this.b(iinventory, enumdirection)) {
                 return false;
             } else {
+                return hopperPush(iinventory, enumdirection); /* // Paper - disable rest
                 for (int i = 0; i < this.getSize(); ++i) {
                     if (!this.getItem(i).isEmpty()) {
                         ItemStack itemstack = this.getItem(i).cloneItemStack();
@@ -216,7 +371,7 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
                     }
                 }
 
-                return false;
+                return false;*/ // Paper - end commenting out replaced block for Hopper Optimizations
             }
         }
     }
@@ -225,18 +380,54 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
         return iinventory instanceof IWorldInventory ? IntStream.of(((IWorldInventory) iinventory).getSlotsForFace(enumdirection)) : IntStream.range(0, iinventory.getSize());
     }
 
-    private boolean b(IInventory iinventory, EnumDirection enumdirection) {
-        return a(iinventory, enumdirection).allMatch((i) -> {
-            ItemStack itemstack = iinventory.getItem(i);
+    private static boolean allMatch(IInventory iinventory, EnumDirection enumdirection, java.util.function.BiPredicate<ItemStack, Integer> test) {
+        if (iinventory instanceof IWorldInventory) {
+            for (int i : ((IWorldInventory) iinventory).getSlotsForFace(enumdirection)) {
+                if (!test.test(iinventory.getItem(i), i)) {
+                    return false;
+                }
+            }
+        } else {
+            int size = iinventory.getSize();
+            for (int i = 0; i < size; i++) {
+                if (!test.test(iinventory.getItem(i), i)) {
+                    return false;
+                }
+            }
+        }
+        return true;
+    }
 
-            return itemstack.getCount() >= itemstack.getMaxStackSize();
-        });
+    private static boolean anyMatch(IInventory iinventory, EnumDirection enumdirection, java.util.function.BiPredicate<ItemStack, Integer> test) {
+        if (iinventory instanceof IWorldInventory) {
+            for (int i : ((IWorldInventory) iinventory).getSlotsForFace(enumdirection)) {
+                if (test.test(iinventory.getItem(i), i)) {
+                    return true;
+                }
+            }
+        } else {
+            int size = iinventory.getSize();
+            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 boolean b(IInventory iinventory, EnumDirection enumdirection) {
+        // Paper start - no streams
+        return allMatch(iinventory, enumdirection, STACK_SIZE_TEST);
+        // Paper end
     }
 
     private static boolean c(IInventory iinventory, EnumDirection enumdirection) {
-        return a(iinventory, enumdirection).allMatch((i) -> {
-            return iinventory.getItem(i).isEmpty();
-        });
+        return allMatch(iinventory, enumdirection, IS_EMPTY_TEST);
     }
 
     public static boolean a(IHopper ihopper) {
@@ -245,9 +436,17 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
         if (iinventory != null) {
             EnumDirection enumdirection = EnumDirection.DOWN;
 
-            return c(iinventory, enumdirection) ? false : a(iinventory, enumdirection).anyMatch((i) -> {
-                return a(ihopper, iinventory, i, enumdirection);
+            // Paper start - optimize hoppers and remove streams
+            skipPullModeEventFire = skipHopperEvents;
+            return !c(iinventory, enumdirection) && anyMatch(iinventory, enumdirection, (item, i) -> {
+                // Logic copied from below to avoid extra getItem calls
+                if (!item.isEmpty() && canTakeItem(iinventory, item, i, enumdirection)) {
+                    return hopperPull(ihopper, iinventory, item, i);
+                } else {
+                    return false;
+                }
             });
+            // Paper end
         } else {
             Iterator iterator = c(ihopper).iterator();
 
@@ -265,10 +464,11 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
         }
     }
 
-    private static boolean a(IHopper ihopper, IInventory iinventory, int i, EnumDirection enumdirection) {
+    private static boolean a(IHopper ihopper, IInventory iinventory, int i, EnumDirection enumdirection) {// Paper - method unused as logic is inlined above
         ItemStack itemstack = iinventory.getItem(i);
 
-        if (!itemstack.isEmpty() && b(iinventory, itemstack, i, enumdirection)) {
+        if (!itemstack.isEmpty() && b(iinventory, itemstack, i, enumdirection)) { // If this logic changes, update above. this is left inused incase reflective plugins
+            return hopperPull(ihopper, iinventory, itemstack, i); /* // Paper - disable rest
             ItemStack itemstack1 = itemstack.cloneItemStack();
             // ItemStack itemstack2 = addItem(iinventory, ihopper, iinventory.splitStack(i, 1), (EnumDirection) null);
             // CraftBukkit start - Call event on collection of items from inventories into the hopper
@@ -305,7 +505,7 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
             }
 
             itemstack1.subtract(origCount - itemstack2.getCount()); // Spigot
-            iinventory.setItem(i, itemstack1);
+            iinventory.setItem(i, itemstack1);*/ // Paper - end commenting out replaced block for Hopper Optimizations
         }
 
         return false;
@@ -314,7 +514,7 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
     public static boolean a(IInventory iinventory, EntityItem entityitem) {
         boolean flag = false;
         // CraftBukkit start
-        InventoryPickupItemEvent event = new InventoryPickupItemEvent(iinventory.getOwner().getInventory(), (org.bukkit.entity.Item) entityitem.getBukkitEntity());
+        InventoryPickupItemEvent event = new InventoryPickupItemEvent(getInventory(iinventory), (org.bukkit.entity.Item) entityitem.getBukkitEntity()); // Paper - use getInventory() to avoid snapshot creation
         entityitem.world.getServer().getPluginManager().callEvent(event);
         if (event.isCancelled()) {
             return false;
@@ -356,6 +556,7 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
         return !iinventory.b(i, itemstack) ? false : !(iinventory instanceof IWorldInventory) || ((IWorldInventory) iinventory).canPlaceItemThroughFace(i, itemstack, enumdirection);
     }
 
+    private static boolean canTakeItem(IInventory iinventory, ItemStack itemstack, int i, EnumDirection enumdirection) { return b(iinventory, itemstack, i, enumdirection); } // Paper - OBFHELPER
     private static boolean b(IInventory iinventory, ItemStack itemstack, int i, EnumDirection enumdirection) {
         return !(iinventory instanceof IWorldInventory) || ((IWorldInventory) iinventory).canTakeItemThroughFace(i, itemstack, enumdirection);
     }
@@ -368,7 +569,9 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
             boolean flag1 = iinventory1.isEmpty();
 
             if (itemstack1.isEmpty()) {
+                IGNORE_TILE_UPDATES = true; // Paper
                 iinventory1.setItem(i, itemstack);
+                IGNORE_TILE_UPDATES = false; // Paper
                 itemstack = ItemStack.b;
                 flag = true;
             } else if (a(itemstack1, itemstack)) {
@@ -419,18 +622,24 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
     }
 
     public static List<EntityItem> c(IHopper ihopper) {
-        return (List) ihopper.aa_().d().stream().flatMap((axisalignedbb) -> {
-            return ihopper.getWorld().a(EntityItem.class, axisalignedbb.d(ihopper.x() - 0.5D, ihopper.z() - 0.5D, ihopper.A() - 0.5D), IEntitySelector.a).stream();
-        }).collect(Collectors.toList());
+        // Paper start - Optimize item suck in. remove streams, restore 1.12 checks. Seriously checking the bowl?!
+        World world = ihopper.getWorld();
+        double d0 = ihopper.getX();
+        double d1 = ihopper.getY();
+        double d2 = ihopper.getZ();
+        AxisAlignedBB bb = new AxisAlignedBB(d0 - 0.5D, d1, d2 - 0.5D, d0 + 0.5D, d1 + 1.5D, d2 + 0.5D);
+        return world.getEntities(EntityItem.class, bb, Entity::isAlive);
+        // Paper end
     }
 
     @Nullable
     public static IInventory b(World world, BlockPosition blockposition) {
-        return a(world, (double) blockposition.getX() + 0.5D, (double) blockposition.getY() + 0.5D, (double) blockposition.getZ() + 0.5D);
+        return a(world, (double) blockposition.getX() + 0.5D, (double) blockposition.getY() + 0.5D, (double) blockposition.getZ() + 0.5D, true); // Paper
     }
 
     @Nullable
-    public static IInventory a(World world, double d0, double d1, double d2) {
+    public static IInventory a(World world, double d0, double d1, double d2) { return a(world, d0, d1, d2, false); } // Paper - overload to default false
+    public static IInventory a(World world, double d0, double d1, double d2, boolean optimizeEntities) { // Paper
         Object object = null;
         BlockPosition blockposition = new BlockPosition(d0, d1, d2);
         if ( !world.isLoaded( blockposition ) ) return null; // Spigot
@@ -450,7 +659,7 @@ public class TileEntityHopper extends TileEntityLootable implements IHopper, ITi
             }
         }
 
-        if (object == null) {
+        if (object == null && (!optimizeEntities || !org.bukkit.craftbukkit.util.CraftMagicNumbers.getMaterial(block).isOccluding())) { // Paper
             List<Entity> list = world.getEntities((Entity) null, new AxisAlignedBB(d0 - 0.5D, d1 - 0.5D, d2 - 0.5D, d0 + 0.5D, d1 + 0.5D, d2 + 0.5D), IEntitySelector.d);
 
             if (!list.isEmpty()) {
diff --git a/src/main/java/net/minecraft/server/TileEntityLootable.java b/src/main/java/net/minecraft/server/TileEntityLootable.java
index c6e6c54a3eb5d725b71f2ec2bb27dd8e2aceabde..c79ebe2343cc14f113c0cc6496c20e7d7bf6fd32 100644
--- a/src/main/java/net/minecraft/server/TileEntityLootable.java
+++ b/src/main/java/net/minecraft/server/TileEntityLootable.java
@@ -77,12 +77,19 @@ public abstract class TileEntityLootable extends TileEntityContainer {
     @Override
     public boolean isEmpty() {
         this.d((EntityHuman) null);
-        return this.f().stream().allMatch(ItemStack::isEmpty);
+        // Paper start
+        for (ItemStack itemStack : this.f()) {
+            if (!itemStack.isEmpty()) {
+                return false;
+            }
+        }
+        // Paper end
+        return true;
     }
 
     @Override
     public ItemStack getItem(int i) {
-        this.d((EntityHuman) null);
+        if (i == 0) this.d((EntityHuman) null); // Paper
         return (ItemStack) this.f().get(i);
     }
 
diff --git a/src/main/java/net/minecraft/server/World.java b/src/main/java/net/minecraft/server/World.java
index 8426bf5b16bbe7c9a8b1582e1dac0298898eb263..303d82bf4ba21b4a74805750650d07778b30d875 100644
--- a/src/main/java/net/minecraft/server/World.java
+++ b/src/main/java/net/minecraft/server/World.java
@@ -1099,8 +1099,8 @@ public abstract class World implements GeneratorAccess, AutoCloseable {
         return list;
     }
 
-    @Override
-    public <T extends Entity> List<T> a(Class<? extends T> oclass, AxisAlignedBB axisalignedbb, @Nullable Predicate<? super T> predicate) {
+    public <T extends Entity> List<T> getEntities(Class<? extends T> oclass, AxisAlignedBB axisalignedbb, @Nullable Predicate<? super T> predicate) { return a(oclass, axisalignedbb, predicate); } // Paper - OBFHELPER
+    @Override public <T extends Entity> List<T> a(Class<? extends T> oclass, AxisAlignedBB axisalignedbb, @Nullable Predicate<? super T> predicate) {
         this.getMethodProfiler().c("getEntities");
         int i = MathHelper.floor((axisalignedbb.minX - 2.0D) / 16.0D);
         int j = MathHelper.f((axisalignedbb.maxX + 2.0D) / 16.0D);