Paper/CraftBukkit-Patches/0161-Use-FastMatches-for-ItemStack-Dirty-Check.patch

From 19582c9dcb154e6202f8421dfbede41ea785d7d9 Mon Sep 17 00:00:00 2001
From: md_5 <git@md-5.net>
Date: Sun, 22 Feb 2015 12:27:40 +1100
Subject: [PATCH] Use FastMatches for ItemStack Dirty Check

The check to find dirty itemstacks and send update packets each tick can be very intensive as it checks the entire itemstack, including the entire NBT map. To save on this, 19/20 times we will simply compare the basic count/data/type. If for some strange reason the NBT of an item already existing in an inventory is changes, it will take up to 1 second to show, with an average time of half a second. This odd 0.5 second delay is far preferable to lag every tick, and shouldn't be noticed by anyone.

diff --git a/src/main/java/net/minecraft/server/Container.java b/src/main/java/net/minecraft/server/Container.java
index 9a12b07..2cfc42d 100644
--- a/src/main/java/net/minecraft/server/Container.java
+++ b/src/main/java/net/minecraft/server/Container.java
@@ -28,6 +28,7 @@ public abstract class Container {
     private final Set h = Sets.newHashSet();
     protected List listeners = Lists.newArrayList();
     private Set i = Sets.newHashSet();
+    private int tickCount; // Spigot
     
     // CraftBukkit start
     public boolean checkReachable = true;
@@ -75,7 +76,7 @@ public abstract class Container {
             ItemStack itemstack = ((Slot) this.c.get(i)).getItem();
             ItemStack itemstack1 = (ItemStack) this.b.get(i);
 
-            if (!ItemStack.matches(itemstack1, itemstack)) {
+            if (!ItemStack.fastMatches(itemstack1, itemstack) || (tickCount % 20 == 0 && !ItemStack.matches(itemstack1, itemstack))) { // Spigot
                 itemstack1 = itemstack == null ? null : itemstack.cloneItemStack();
                 this.b.set(i, itemstack1);
 
@@ -84,6 +85,7 @@ public abstract class Container {
                 }
             }
         }
+        tickCount++; // Spigot
 
     }
 
diff --git a/src/main/java/net/minecraft/server/ItemStack.java b/src/main/java/net/minecraft/server/ItemStack.java
index 596db09..169706e 100644
--- a/src/main/java/net/minecraft/server/ItemStack.java
+++ b/src/main/java/net/minecraft/server/ItemStack.java
@@ -439,6 +439,18 @@ public final class ItemStack {
         return itemstack == null && itemstack1 == null ? true : (itemstack != null && itemstack1 != null ? (itemstack.tag == null && itemstack1.tag != null ? false : itemstack.tag == null || itemstack.tag.equals(itemstack1.tag)) : false);
     }
 
+    // Spigot Start
+    public static boolean fastMatches(ItemStack itemstack, ItemStack itemstack1) {
+        if (itemstack == null && itemstack1 == null) {
+            return true;
+        }
+        if (itemstack != null && itemstack1 != null) {
+            return itemstack.count == itemstack1.count && itemstack.item == itemstack1.item && itemstack.damage == itemstack1.damage;
+        }
+        return false;
+    }
+    // Spigot End
+
     public static boolean matches(ItemStack itemstack, ItemStack itemstack1) {
         return itemstack == null && itemstack1 == null ? true : (itemstack != null && itemstack1 != null ? itemstack.d(itemstack1) : false);
     }
-- 
2.1.0