Reuse ItemExternalStorageCache to avoid excessive calls to getStackInSlot

src/main/java/com/refinedmods/refinedstorage/apiimpl/storage/externalstorage/ItemExternalStorage.java

@@ -137,19 +137,7 @@ public class ItemExternalStorage implements IExternalStorage<ItemStack> {
 
     @Override
     public int getStored() {
-        IItemHandler handler = handlerSupplier.get();
-
-        if (handler == null) {
-            return 0;
-        }
-
-        int size = 0;
-
-        for (int i = 0; i < handler.getSlots(); ++i) {
-            size += handler.getStackInSlot(i).getCount();
-        }
-
-        return size;
+        return cache.getStored();
     }
 
     @Override

src/main/java/com/refinedmods/refinedstorage/apiimpl/storage/externalstorage/ItemExternalStorageCache.java

@@ -11,24 +11,36 @@ import java.util.List;
 
 public class ItemExternalStorageCache {
     private List<ItemStack> cache;
+    private int stored = 0;
+
+    public int getStored() {
+        return stored;
+    }
 
     public void update(INetwork network, @Nullable IItemHandler handler) {
         if (handler == null) {
+            stored = 0;
             return;
         }
 
         if (cache == null) {
             cache = new ArrayList<>();
 
+            int stored = 0;
             for (int i = 0; i < handler.getSlots(); ++i) {
-                cache.add(handler.getStackInSlot(i).copy());
+                ItemStack stack = handler.getStackInSlot(i).copy();
+                cache.add(stack);
+                stored += stack.getCount();
             }
+            this.stored = stored;
 
             return;
         }
 
+        int stored = 0;
         for (int i = 0; i < handler.getSlots(); ++i) {
             ItemStack actual = handler.getStackInSlot(i);
+            stored += actual.getCount();
 
             if (i >= cache.size()) { // ENLARGED
                 if (!actual.isEmpty()) {
@@ -69,6 +81,7 @@ public class ItemExternalStorageCache {
                 }
             }
         }
+        this.stored = stored;
 
         if (cache.size() > handler.getSlots()) { // SHRUNK
             for (int i = cache.size() - 1; i >= handler.getSlots(); --i) { // Reverse order for the remove call.