feat: optimize item stack handling by using getTemplateRef() to reduce cloning

Author: ptthanh02

core/src/main/java/github/nighter/smartspawner/spawner/properties/SpawnerData.java

@@ -519,7 +519,8 @@ public void incrementSellValue(Map<VirtualInventory.ItemSignature, Long> itemsAd
 
         double addedValue = 0.0;
         for (Map.Entry<VirtualInventory.ItemSignature, Long> entry : itemsAdded.entrySet()) {
-            ItemStack template = entry.getKey().getTemplate();
+            // Use getTemplateRef() to avoid cloning - we only need to read properties
+            ItemStack template = entry.getKey().getTemplateRef();
             long amount = entry.getValue();
             double itemPrice = findItemPrice(template, priceCache);
             if (itemPrice > 0.0) {
@@ -552,7 +553,8 @@ public void decrementSellValue(List<ItemStack> itemsRemoved, Map<String, Double>
 
         double removedValue = 0.0;
         for (Map.Entry<VirtualInventory.ItemSignature, Long> entry : consolidated.entrySet()) {
-            ItemStack template = entry.getKey().getTemplate();
+            // Use getTemplateRef() to avoid cloning - we only need to read properties
+            ItemStack template = entry.getKey().getTemplateRef();
             long amount = entry.getValue();
             double itemPrice = findItemPrice(template, priceCache);
             if (itemPrice > 0.0) {
@@ -582,7 +584,8 @@ public void recalculateSellValue() {
         double totalValue = 0.0;
 
         for (Map.Entry<VirtualInventory.ItemSignature, Long> entry : items.entrySet()) {
-            ItemStack template = entry.getKey().getTemplate();
+            // Use getTemplateRef() to avoid cloning - we only need to read properties
+            ItemStack template = entry.getKey().getTemplateRef();
             long amount = entry.getValue();
             double itemPrice = findItemPrice(template, priceCache);
             if (itemPrice > 0.0) {

core/src/main/java/github/nighter/smartspawner/spawner/properties/VirtualInventory.java

@@ -164,7 +164,8 @@ public boolean removeItems(List<ItemStack> items) {
         // Calculate total amounts to remove in a single pass
         for (ItemStack item : items) {
             if (item == null || item.getAmount() <= 0) continue;
-            ItemSignature sig = new ItemSignature(item);
+            // Use cached signature to avoid excessive cloning
+            ItemSignature sig = getSignature(item);
             toRemove.merge(sig, (long) item.getAmount(), Long::sum);
         }
 

core/src/main/java/github/nighter/smartspawner/spawner/sell/SpawnerSellManager.java

@@ -177,29 +177,42 @@ private void processSellResult(Player player, SpawnerData spawner, SellResult se
     /**
      * Calculates the total sell value of items using cached accumulated value
      * This method is optimized to use pre-calculated sell values
+     * OPTIMIZED: Single-pass iteration with progressive capacity adjustment
      */
     private SellResult calculateSellValue(Map<VirtualInventory.ItemSignature, Long> consolidatedItems,
                                           SpawnerData spawner) {
         // Use the accumulated sell value from spawner (already calculated incrementally)
         double totalValue = spawner.getAccumulatedSellValue();
         long totalItemsSold = 0;
-        List<ItemStack> itemsToRemove = new ArrayList<>();
 
-        // We still need to create the items list for removal
+        // Start with reasonable initial capacity (will grow progressively)
+        // Use ArrayList directly to access ensureCapacity method
+        ArrayList<ItemStack> itemsToRemove = new ArrayList<>();
+
+        // Single-pass iteration: calculate stacks needed AND create them
         for (Map.Entry<VirtualInventory.ItemSignature, Long> entry : consolidatedItems.entrySet()) {
-            ItemStack template = entry.getKey().getTemplate();
+            // Use getTemplateRef() to avoid cloning when reading properties
+            ItemStack templateRef = entry.getKey().getTemplateRef();
             long amount = entry.getValue();
-            
-            // Count items (we need this even if we skip price calculation)
+            int maxStackSize = templateRef.getMaxStackSize();
+
+            // Count items for statistics
             totalItemsSold += amount;
 
+            // Calculate how many stacks this item type needs
+            int stacksNeeded = (int) Math.ceil((double) amount / maxStackSize);
+
+            // Ensure capacity before adding to avoid resizing during loop
+            // This is cheaper than multiple resizes
+            itemsToRemove.ensureCapacity(itemsToRemove.size() + stacksNeeded);
+
             // Create ItemStacks to remove (handle stacking properly)
             long remainingAmount = amount;
             while (remainingAmount > 0) {
-                ItemStack stackToRemove = template.clone();
-                int stackSize = (int) Math.min(remainingAmount, template.getMaxStackSize());
+                ItemStack stackToRemove = templateRef.clone(); // Single clone per stack
+                int stackSize = (int) Math.min(remainingAmount, maxStackSize);
                 stackToRemove.setAmount(stackSize);
-                itemsToRemove.add(stackToRemove);
+                itemsToRemove.add(stackToRemove); // No resize thanks to ensureCapacity
                 remainingAmount -= stackSize;
             }
         }

core/src/main/java/github/nighter/smartspawner/spawner/utils/ItemStackSerializer.java

@@ -42,7 +42,8 @@ public static List<String> serializeInventory(Map<VirtualInventory.ItemSignature
         Map<Material, ItemGroup> groupedItems = new HashMap<>();
 
         for (Map.Entry<VirtualInventory.ItemSignature, Long> entry : items.entrySet()) {
-            ItemStack template = entry.getKey().getTemplate();
+            // Use getTemplateRef() to avoid cloning - we only need to read properties
+            ItemStack template = entry.getKey().getTemplateRef();
             Material material = template.getType();
             ItemGroup group = groupedItems.computeIfAbsent(material, ItemGroup::new);