Force volatile read for inventory contents

src/main/java/net/minestom/server/inventory/AbstractInventory.java

@@ -1,5 +1,8 @@
 package net.minestom.server.inventory;
 
+import net.minestom.server.event.GlobalHandles;
+import net.minestom.server.event.inventory.InventoryItemChangeEvent;
+import net.minestom.server.event.inventory.PlayerInventoryItemChangeEvent;
 import net.minestom.server.inventory.click.InventoryClickProcessor;
 import net.minestom.server.inventory.condition.InventoryCondition;
 import net.minestom.server.item.ItemStack;
@@ -9,9 +12,10 @@ import net.minestom.server.utils.MathUtils;
 import net.minestom.server.utils.validate.Check;
 import org.jetbrains.annotations.NotNull;
 import org.jetbrains.annotations.Nullable;
-import org.jglrxavpok.hephaistos.nbt.NBTCompound;
 import org.jglrxavpok.hephaistos.nbt.mutable.MutableNBTCompound;
 
+import java.lang.invoke.MethodHandles;
+import java.lang.invoke.VarHandle;
 import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.List;
@@ -24,6 +28,8 @@ import java.util.function.UnaryOperator;
 public sealed abstract class AbstractInventory implements InventoryClickHandler, TagHandler
         permits Inventory, PlayerInventory {
 
+    private static final VarHandle ITEM_UPDATER = MethodHandles.arrayElementVarHandle(ItemStack[].class);
+
     private final int size;
     protected final ItemStack[] itemStacks;
 
@@ -38,7 +44,6 @@ public sealed abstract class AbstractInventory implements InventoryClickHandler,
     protected AbstractInventory(int size) {
         this.size = size;
         this.itemStacks = new ItemStack[getSize()];
-
         Arrays.fill(itemStacks, ItemStack.AIR);
     }
 
@@ -62,7 +67,6 @@ public sealed abstract class AbstractInventory implements InventoryClickHandler,
      *
      * @param slot      the internal slot id
      * @param itemStack the item to insert (use air instead of null)
-     *
      * @throws IllegalArgumentException if the slot {@code slot} does not exist
      */
     protected final void safeItemInsert(int slot, @NotNull ItemStack itemStack) {
@@ -76,13 +80,15 @@ public sealed abstract class AbstractInventory implements InventoryClickHandler,
             previous = itemStacks[slot];
             UNSAFE_itemInsert(slot, itemStack);
         }
-        callItemChangeEvent(slot, previous, itemStack);
+        if (this instanceof PlayerInventory inv) {
+            GlobalHandles.PLAYER_INVENTORY_ITEM_CHANGE_EVENT.call(new PlayerInventoryItemChangeEvent(inv.player, slot, previous, itemStack));
+        } else if (this instanceof Inventory inv) {
+            GlobalHandles.INVENTORY_ITEM_CHANGE_EVENT.call(new InventoryItemChangeEvent(inv, slot, previous, itemStack));
+        }
     }
 
     protected abstract void UNSAFE_itemInsert(int slot, @NotNull ItemStack itemStack);
 
-    protected abstract void callItemChangeEvent(int slot, @NotNull ItemStack previous, @NotNull ItemStack current);
-
     public synchronized <T> @NotNull T processItemStack(@NotNull ItemStack itemStack,
                                                         @NotNull TransactionType type,
                                                         @NotNull TransactionOption<T> option) {
@@ -172,7 +178,7 @@ public sealed abstract class AbstractInventory implements InventoryClickHandler,
      * @return the item in the slot {@code slot}
      */
     public @NotNull ItemStack getItemStack(int slot) {
-        return itemStacks[slot];
+        return (ItemStack) ITEM_UPDATER.getVolatile(itemStacks, slot);
     }
 
     /**

src/main/java/net/minestom/server/inventory/Inventory.java

@@ -3,8 +3,6 @@ package net.minestom.server.inventory;
 import net.kyori.adventure.text.Component;
 import net.minestom.server.Viewable;
 import net.minestom.server.entity.Player;
-import net.minestom.server.event.GlobalHandles;
-import net.minestom.server.event.inventory.InventoryItemChangeEvent;
 import net.minestom.server.inventory.click.ClickType;
 import net.minestom.server.inventory.click.InventoryClickResult;
 import net.minestom.server.item.ItemStack;
@@ -72,8 +70,7 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
      *
      * @return the inventory type
      */
-    @NotNull
+    public @NotNull InventoryType getInventoryType() {
-    public InventoryType getInventoryType() {
         return inventoryType;
     }
 
@@ -82,8 +79,7 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
      *
      * @return the inventory title
      */
-    @NotNull
+    public @NotNull Component getTitle() {
-    public Component getTitle() {
         return title;
     }
 
@@ -124,9 +120,7 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
      */
     @Override
     public void update() {
-        for (Player player : viewers) {
+        this.viewers.forEach(p -> p.sendPacket(createNewWindowItemsPacket(p)));
-            player.sendPacket(createNewWindowItemsPacket(player));
-        }
     }
 
     /**
@@ -141,9 +135,8 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
         player.sendPacket(createNewWindowItemsPacket(player));
     }
 
-    @NotNull
     @Override
-    public Set<Player> getViewers() {
+    public @NotNull Set<Player> getViewers() {
         return unmodifiableViewers;
     }
 
@@ -180,8 +173,7 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
      * @param player the player to get the cursor item from
      * @return the player cursor item, air item if the player is not a viewer
      */
-    @NotNull
+    public @NotNull ItemStack getCursorItem(@NotNull Player player) {
-    public ItemStack getCursorItem(@NotNull Player player) {
         return cursorPlayersItem.getOrDefault(player, ItemStack.AIR);
     }
 
@@ -210,16 +202,6 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
         sendPacketToViewers(new SetSlotPacket(getWindowId(), 0, (short) slot, itemStack));
     }
 
-    @Override
-    protected void callItemChangeEvent(int slot, @NotNull ItemStack previous, @NotNull ItemStack current) {
-        GlobalHandles.INVENTORY_ITEM_CHANGE_EVENT.call(new InventoryItemChangeEvent(this, slot, previous, current));
-    }
-
-    /**
-     * Creates a complete new {@link WindowItemsPacket}.
-     *
-     * @return a new {@link WindowItemsPacket} packet
-     */
     private @NotNull WindowItemsPacket createNewWindowItemsPacket(Player player) {
         return new WindowItemsPacket(getWindowId(), 0, List.of(getItemStacks()), cursorPlayersItem.getOrDefault(player, ItemStack.AIR));
     }
@@ -235,22 +217,6 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
         sendPacketToViewers(new WindowPropertyPacket(getWindowId(), property.getProperty(), value));
     }
 
-    /**
-     * Changes the internal player's cursor item
-     * <p>
-     * WARNING: the player will not be notified by the change
-     *
-     * @param player    the player to change the cursor item
-     * @param itemStack the cursor item
-     */
-    private void refreshPlayerCursorItem(@NotNull Player player, @NotNull ItemStack itemStack) {
-        this.cursorPlayersItem.put(player, itemStack);
-    }
-
-    private boolean isClickInWindow(int slot) {
-        return slot < getSize();
-    }
-
     @Override
     public boolean leftClick(@NotNull Player player, int slot) {
         final PlayerInventory playerInventory = player.getInventory();
@@ -269,7 +235,7 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
         } else {
             playerInventory.setItemStack(clickSlot, clickResult.getClicked());
         }
-        refreshPlayerCursorItem(player, clickResult.getCursor());
+        this.cursorPlayersItem.put(player, clickResult.getCursor());
         callClickEvent(player, isInWindow ? this : null, slot, ClickType.LEFT_CLICK, clicked, cursor);
         return true;
     }
@@ -292,7 +258,7 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
         } else {
             playerInventory.setItemStack(clickSlot, clickResult.getClicked());
         }
-        refreshPlayerCursorItem(player, clickResult.getCursor());
+        this.cursorPlayersItem.put(player, clickResult.getCursor());
         callClickEvent(player, isInWindow ? this : null, slot, ClickType.RIGHT_CLICK, clicked, cursor);
         return true;
     }
@@ -319,7 +285,7 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
             playerInventory.setItemStack(clickSlot, clickResult.getClicked());
         }
         updateAll(player); // FIXME: currently not properly client-predicted
-        refreshPlayerCursorItem(player, clickResult.getCursor());
+        this.cursorPlayersItem.put(player, clickResult.getCursor());
         return true;
     }
 
@@ -376,7 +342,7 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
                 playerInventory.setItemStack(clickSlot, resultClicked);
             }
         }
-        refreshPlayerCursorItem(player, clickResult.getCursor());
+        this.cursorPlayersItem.put(player, clickResult.getCursor());
         return true;
     }
 
@@ -397,7 +363,7 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
             updateAll(player);
             return false;
         }
-        refreshPlayerCursorItem(player, clickResult.getCursor());
+        this.cursorPlayersItem.put(player, clickResult.getCursor());
         updateAll(player); // FIXME: currently not properly client-predicted
         return true;
     }
@@ -417,11 +383,15 @@ public non-sealed class Inventory extends AbstractInventory implements Viewable
             updateAll(player);
             return false;
         }
-        refreshPlayerCursorItem(player, clickResult.getCursor());
+        this.cursorPlayersItem.put(player, clickResult.getCursor());
         updateAll(player); // FIXME: currently not properly client-predicted
         return true;
     }
 
+    private boolean isClickInWindow(int slot) {
+        return slot < getSize();
+    }
+
     private void updateAll(Player player) {
         player.getInventory().update();
         update(player);

src/main/java/net/minestom/server/inventory/PlayerInventory.java

@@ -3,8 +3,6 @@ package net.minestom.server.inventory;
 import net.minestom.server.entity.EquipmentSlot;
 import net.minestom.server.entity.Player;
 import net.minestom.server.event.EventDispatcher;
-import net.minestom.server.event.GlobalHandles;
-import net.minestom.server.event.inventory.PlayerInventoryItemChangeEvent;
 import net.minestom.server.event.item.EntityEquipEvent;
 import net.minestom.server.inventory.click.ClickType;
 import net.minestom.server.inventory.click.InventoryClickResult;
@@ -169,11 +167,6 @@ public non-sealed class PlayerInventory extends AbstractInventory implements Equ
         sendSlotRefresh((short) convertToPacketSlot(slot), itemStack);
     }
 
-    @Override
-    protected void callItemChangeEvent(int slot, @NotNull ItemStack previous, @NotNull ItemStack current) {
-        GlobalHandles.PLAYER_INVENTORY_ITEM_CHANGE_EVENT.call(new PlayerInventoryItemChangeEvent(player, slot, previous, current));
-    }
-
     /**
      * Refreshes an inventory slot.
      *