Don't rebuild the whole item cache on an external inventory change

src/main/java/com/raoulvdberge/refinedstorage/apiimpl/storage/item/ItemStorageCache.java

@@ -39,7 +39,9 @@ public class ItemStorageCache implements IItemStorageCache {
             }
 
             for (ItemStack stack : storage.getStacks()) {
-                add(stack, true);
+                if (stack != null) {
+                    add(stack, true);
+                }
             }
         }
 

src/main/java/com/raoulvdberge/refinedstorage/tile/TileController.java

@@ -530,13 +530,13 @@ public class TileController extends TileBase implements INetworkMaster, IEnergyR
 
             if (remainder == null || remainder.stackSize < 0) {
                 if (storage instanceof ItemStorageExternal && !simulate) {
-                    ((ItemStorageExternal) storage).updateCacheForcefully();
+                    ((ItemStorageExternal) storage).updateForced();
                 }
 
                 break;
             } else {
                 if (size != remainder.stackSize && storage instanceof ItemStorageExternal && !simulate) {
-                    ((ItemStorageExternal) storage).updateCacheForcefully();
+                    ((ItemStorageExternal) storage).updateForced();
                 }
 
                 size = remainder.stackSize;
@@ -586,7 +586,7 @@ public class TileController extends TileBase implements INetworkMaster, IEnergyR
 
             if (took != null) {
                 if (storage instanceof ItemStorageExternal) {
-                    ((ItemStorageExternal) storage).updateCacheForcefully();
+                    ((ItemStorageExternal) storage).updateForced();
                 }
 
                 if (newStack == null) {

src/main/java/com/raoulvdberge/refinedstorage/tile/externalstorage/ItemStorageExternal.java

@@ -1,9 +1,12 @@
 package com.raoulvdberge.refinedstorage.tile.externalstorage;
 
+import com.raoulvdberge.refinedstorage.api.network.INetworkMaster;
 import com.raoulvdberge.refinedstorage.api.storage.item.IItemStorage;
 import com.raoulvdberge.refinedstorage.apiimpl.API;
 import net.minecraft.item.ItemStack;
+import net.minecraftforge.items.ItemHandlerHelper;
 
+import java.util.LinkedList;
 import java.util.List;
 
 public abstract class ItemStorageExternal implements IItemStorage {
@@ -11,29 +14,67 @@ public abstract class ItemStorageExternal implements IItemStorage {
 
     public abstract int getCapacity();
 
-    public boolean updateCache() {
+    public void detectChanges(INetworkMaster network) {
-        List<ItemStack> newStacks = getStacks();
+        if (cache == null) {
-
+            updateForced();
-        if (this.cache == null) {
-            this.cache = newStacks;
-        } else if (newStacks.size() != cache.size()) {
-            this.cache = newStacks;
-
-            return true;
         } else {
-            for (int i = 0; i < newStacks.size(); ++i) {
+            LinkedList<ItemStack> changes = new LinkedList<>();
-                if (!API.instance().getComparer().isEqual(newStacks.get(i), cache.get(i))) {
-                    this.cache = newStacks;
 
-                    return true;
+            List<ItemStack> newStacks = getStacks();
+
+            for (int i = 0; i < newStacks.size(); ++i) {
+                ItemStack actual = newStacks.get(i);
+
+                // If we exceed the cache size, than that means this items is added
+                if (i >= cache.size()) {
+                    if (actual != null) {
+                        changes.add(ItemHandlerHelper.copyStackWithSize(actual, actual.stackSize));
+                    }
+
+                    continue;
+                }
+
+                ItemStack cached = cache.get(i);
+
+                if (cached != null && actual == null) {
+                    // If the cached is not null but the actual is, we removed this item
+                    changes.add(ItemHandlerHelper.copyStackWithSize(cached, -cached.stackSize));
+                } else if (cached == null && actual != null) {
+                    // If the cached is null and the actual isn't, we added this item
+                    changes.add(ItemHandlerHelper.copyStackWithSize(actual, actual.stackSize));
+                } else if (cached == null && actual == null) {
+                    // If they're both null, nothing happens
+                } else if (!API.instance().getComparer().isEqualNoQuantity(cached, actual)) {
+                    // If both items mismatch, remove the old and add the new
+                    changes.add(ItemHandlerHelper.copyStackWithSize(cached, -cached.stackSize));
+                    changes.add(ItemHandlerHelper.copyStackWithSize(actual, actual.stackSize));
+                } else if (cached.stackSize != actual.stackSize) {
+                    // If both items mismatch on itemcount, apply the change
+                    changes.add(ItemHandlerHelper.copyStackWithSize(cached, actual.stackSize - cached.stackSize));
+                }
+            }
+
+            // If the cache size is somehow bigger than the actual stacks, that means the inventory shrunk
+            // In that case, we remove the items that have been removed due to the shrinkage
+            if (cache.size() > newStacks.size()) {
+                for (int i = newStacks.size(); i < cache.size(); ++i) {
+                    changes.add(ItemHandlerHelper.copyStackWithSize(cache.get(i), -cache.get(i).stackSize));
+                }
+            }
+
+            this.cache = newStacks;
+
+            for (ItemStack change : changes) {
+                if (change.stackSize > 0) {
+                    network.getItemStorageCache().add(change, false);
+                } else {
+                    network.getItemStorageCache().remove(change);
                 }
             }
         }
-
-        return false;
     }
 
-    public void updateCacheForcefully() {
+    public void updateForced() {
         this.cache = getStacks();
     }
 }

src/main/java/com/raoulvdberge/refinedstorage/tile/externalstorage/ItemStorageItemHandler.java

@@ -34,9 +34,7 @@ public class ItemStorageItemHandler extends ItemStorageExternal {
         List<ItemStack> items = new ArrayList<>();
 
         for (int i = 0; i < handler.getSlots(); ++i) {
-            if (handler.getStackInSlot(i) != null && handler.getStackInSlot(i).getItem() != null) {
+            items.add(handler.getStackInSlot(i) != null ? handler.getStackInSlot(i).copy() : null);
-                items.add(handler.getStackInSlot(i).copy());
-            }
         }
 
         return items;

src/main/java/com/raoulvdberge/refinedstorage/tile/externalstorage/TileExternalStorage.java

@@ -127,24 +127,18 @@ public class TileExternalStorage extends TileMultipartNode implements IItemStora
     @Override
     public void update() {
         if (!worldObj.isRemote && network != null) {
-            boolean itemChangeDetected = false, fluidChangeDetected = false;
-
             for (ItemStorageExternal storage : itemStorages) {
-                if (storage.updateCache()) {
+                storage.detectChanges(network);
-                    itemChangeDetected = true;
-                }
             }
 
+            boolean fluidChangeDetected = false;
+
             for (FluidStorageExternal storage : fluidStorages) {
                 if (storage.updateCache()) {
                     fluidChangeDetected = true;
                 }
             }
 
-            if (itemChangeDetected) {
-                network.getItemStorageCache().invalidate();
-            }
-
             if (fluidChangeDetected) {
                 network.getFluidStorageCache().invalidate();
             }