Paper/patches/server/0724-Optimize-HashMapPalette.patch
Jake Potrebic 90fe0d58a5
Updated Upstream (Bukkit/CraftBukkit/Spigot) (#9825)
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:
897a0a23 SPIGOT-5753: Back PotionType by a minecraft registry
255b2aa1 SPIGOT-7080: Add World#locateNearestBiome
ff984826 Remove javadoc.io doc links

CraftBukkit Changes:
71b0135cc SPIGOT-5753: Back PotionType by a minecraft registry
a6bcb8489 SPIGOT-7080: Add World#locateNearestBiome
ad0e57434 SPIGOT-7502: CraftMetaItem - cannot deserialize BlockStateTag
b3efca57a SPIGOT-6400: Use Mockito instead of InvocationHandler
38c599f9d PR-1272: Only allow one entity in CraftItem instead of two
f065271ac SPIGOT-7498: ChunkSnapshot.getBlockEmittedLight() gets 64 blocks upper in Overworld

Spigot Changes:
e0e223fe Remove javadoc.io doc links
2023-10-22 20:12:00 +01:00

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 26e093243c70313b777483d9555fb1557443c9b8..7b7b614e5c3a30be89eeea2d25112fc9bcb3052c 100644
--- a/src/main/java/net/minecraft/world/level/chunk/HashMapPalette.java
+++ b/src/main/java/net/minecraft/world/level/chunk/HashMapPalette.java
@@ -20,7 +20,7 @@ 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) {
@@ -38,10 +38,16 @@ 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;