Paper/patches/server/0741-Optimize-HashMapPalette.patch
Nassim Jahnke 275173e538
Updated Upstream (Bukkit/CraftBukkit)
Upstream has released updates that appear to apply and compile correctly.
This update has not been tested by PaperMC and as with ANY update, please do your own testing

Bukkit Changes:
0c5d8709 SPIGOT-7400: Downgrade maven-resolver due to issues resolving certain depends
255c4fdb SPIGOT-7380: Add PlayerInteractEvent#getClickedPosition and ChiseledBookshelf#getSlot

CraftBukkit Changes:
b6b514b7e SPIGOT-7400: Downgrade maven-resolver due to issues resolving certain depends
fcff84de9 SPIGOT-7399: Revert null check in CraftMetaItem#safelyAdd
44a4b5649 SPIGOT-7380: Add PlayerInteractEvent#getClickedPosition and ChiseledBookshelf#getSlot
676969d01 SPIGOT-7389: Handle setting null items in ChiseledBookshelf Inventory
2023-06-18 13:18:11 +02:00

58 lines
3.2 KiB
Diff

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: stonar96 <minecraft.stonar96@gmail.com>
Date: Sun, 17 Jan 2021 01:11:36 +0100
Subject: [PATCH] Optimize HashMapPalette
HashMapPalette uses an instance of CrudeIncrementalIntIdentityHashBiMap
internally. A Palette has a preset maximum size = 1 << bits.
CrudeIncrementalIntIdentityHashBiMap has an initial size but is
automatically resized. The CrudeIncrementalIntIdentityHashBiMap is created
with the maximum size in the constructor of HashMapPalette, with the aim
that it doesn't need to be resized anymore. However, there are two things
that I think Mojang hasn't considered here:
1) The CrudeIncrementalIntIdentityHashBiMap is resized, when its initial
size is reached and not the next time, when a further object is added.
2) HashMapPalette adds objects (unnecessarily) before checking if the
initial size of CrudeIncrementalIntIdentityHashBiMap is reached.
This means to actually avoid resize operations in
CrudeIncrementalIntIdentityHashBiMap, one has to add 2 to the initial size
or add 1 and check the size before adding objects. This commit implements
the second approach. Note that this isn't only an optimization but also
makes async reads of Palettes fail-safe. An async read while the
CrudeIncrementalIntIdentityHashBiMap is resized is fatal and can even lead
to corrupted data. This is also something that Anti-Xray is currently
relying on.
diff --git a/src/main/java/net/minecraft/world/level/chunk/HashMapPalette.java b/src/main/java/net/minecraft/world/level/chunk/HashMapPalette.java
index a6d0008636f72ff6614eda4b1fa856798e6b46fd..50580313a1e224a9569e343ccf4aa0c00b906a30 100644
--- a/src/main/java/net/minecraft/world/level/chunk/HashMapPalette.java
+++ b/src/main/java/net/minecraft/world/level/chunk/HashMapPalette.java
@@ -19,7 +19,7 @@ public class HashMapPalette<T> implements Palette<T> {
}
public HashMapPalette(IdMap<T> idList, int indexBits, PaletteResize<T> listener) {
- this(idList, indexBits, listener, CrudeIncrementalIntIdentityHashBiMap.create(1 << indexBits));
+ this(idList, indexBits, listener, CrudeIncrementalIntIdentityHashBiMap.create((1 << indexBits) + 1)); // Paper - Avoid unnecessary resize operation in CrudeIncrementalIntIdentityHashBiMap
}
private HashMapPalette(IdMap<T> idList, int indexBits, PaletteResize<T> listener, CrudeIncrementalIntIdentityHashBiMap<T> map) {
@@ -37,10 +37,16 @@ public class HashMapPalette<T> implements Palette<T> {
public int idFor(T object) {
int i = this.values.getId(object);
if (i == -1) {
- i = this.values.add(object);
- if (i >= 1 << this.bits) {
+ // Paper start - Avoid unnecessary resize operation in CrudeIncrementalIntIdentityHashBiMap and optimize
+ // We use size() instead of the result from add(K)
+ // This avoids adding another object unnecessarily
+ // Without this change, + 2 would be required in the constructor
+ if (this.values.size() >= 1 << this.bits) {
i = this.resizeHandler.onResize(this.bits + 1, object);
+ } else {
+ i = this.values.add(object);
}
+ // Paper end
}
return i;