PaperMC/patches/server/0808-Optimize-HashMapPalette.patch
Nassim Jahnke 1cfd363d32
Updated Upstream (Bukkit/CraftBukkit/Spigot)
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:
fc460d1b PR-735: Add Villager#zombify
c8c8331e PR-690: Add method to read ItemStack input
62845f2f SPIGOT-6829: Add per-player world border API

CraftBukkit Changes:
a459f4d4 PR-1033: Add Villager#zombify
d65d1430 PR-975: Add method to read ItemStack input
b5559f8c SPIGOT-6990: Fix setRepairCost(0) in Anvil
6c308e1b SPIGOT-6829: Add per-player world border API

Spigot Changes:
42b61526 SPIGOT-7000: Generation and /locate issues when using custom structure seeds
2022-04-16 10:29:50 +02:00

57 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 c5551c31597f5a7fe62ade325e36425e5f2df0b9..ba9b0f419b0785a0b1e3bc57f18bfe5edaa192bd 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> idMap, int i, PaletteResize<T> paletteResize, CrudeIncrementalIntIdentityHashBiMap<T> crudeIncrementalIntIdentityHashBiMap) {
@@ -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;