PaperMC/Spigot-Server-Patches/0078-Optimize-Chunk-Access.patch
Aikar d07f7197f2
Use Last Access Cache for isLoaded calls
this should provide a pretty good across-the-board performance
improvement for the entire server, as it's very common for code
to check if (isLoaded(x, z)) { then do something on that chunk }

Previously, containsKey would not read or set the last access cache

By making it do get() != null, we gain the benefits of last access
and also improves thread safey for async isLoaded checks

This exact usage scenario is used in Entity movement, so that alone
saves us up to 5%~ of CPU time for Entity movement.
2018-10-23 23:50:51 -04:00

125 lines
5.4 KiB
Diff

From 7ac07ac07ac07ac07ac07ac07ac07ac07ac07ac0 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Thu, 27 Aug 2015 01:15:02 -0400
Subject: [PATCH] Optimize Chunk Access
getting a loaded chunk is one of the most hottest pieces of code in the game.
getChunkAt is called for the same chunk multiple times in a row, often from getType();
Optimize this look up by using a Last Access cache.
diff --git a/src/main/java/net/minecraft/server/ChunkMap.java b/src/main/java/net/minecraft/server/ChunkMap.java
index 7ac07ac07ac0..7ac07ac07ac0 100644
--- a/src/main/java/net/minecraft/server/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/ChunkMap.java
@@ -15,6 +15,7 @@ public class ChunkMap extends Long2ObjectOpenHashMap<Chunk> {
public Chunk a(long i, Chunk chunk) {
chunk.world.timings.syncChunkLoadPostTimer.startTiming(); // Paper
+ lastChunkByPos = chunk; // Paper
Chunk chunk1 = (Chunk) super.put(i, chunk);
ChunkCoordIntPair chunkcoordintpair = new ChunkCoordIntPair(i);
@@ -22,7 +23,7 @@ public class ChunkMap extends Long2ObjectOpenHashMap<Chunk> {
for (int k = chunkcoordintpair.z - 1; k <= chunkcoordintpair.z + 1; ++k) {
if (j != chunkcoordintpair.x || k != chunkcoordintpair.z) {
long l = ChunkCoordIntPair.a(j, k);
- Chunk chunk2 = (Chunk) this.get(l);
+ Chunk chunk2 = (Chunk) super.get(l); // Paper - use super to avoid polluting last access cache
if (chunk2 != null) {
chunk.H();
@@ -40,7 +41,7 @@ public class ChunkMap extends Long2ObjectOpenHashMap<Chunk> {
continue;
}
- Chunk neighbor = this.get(ChunkCoordIntPair.a(chunkcoordintpair.x + x, chunkcoordintpair.z + z));
+ Chunk neighbor = super.get(ChunkCoordIntPair.a(chunkcoordintpair.x + x, chunkcoordintpair.z + z)); // Paper - use super to avoid polluting last access cache
if (neighbor != null) {
neighbor.setNeighborLoaded(-x, -z);
chunk.setNeighborLoaded(x, z);
@@ -64,7 +65,7 @@ public class ChunkMap extends Long2ObjectOpenHashMap<Chunk> {
for (int j = chunkcoordintpair.x - 1; j <= chunkcoordintpair.x + 1; ++j) {
for (int k = chunkcoordintpair.z - 1; k <= chunkcoordintpair.z + 1; ++k) {
if (j != chunkcoordintpair.x || k != chunkcoordintpair.z) {
- Chunk chunk1 = (Chunk) this.get(ChunkCoordIntPair.a(j, k));
+ Chunk chunk1 = (Chunk) super.get(ChunkCoordIntPair.a(j, k)); // Paper - use super to avoid polluting last access cache
if (chunk1 != null) {
chunk1.I();
@@ -73,8 +74,22 @@ public class ChunkMap extends Long2ObjectOpenHashMap<Chunk> {
}
}
+ // Paper start
+ if (lastChunkByPos != null && i == lastChunkByPos.chunkKey) {
+ lastChunkByPos = null;
+ }
return chunk;
}
+ private Chunk lastChunkByPos = null;
+
+ @Override
+ public Chunk get(long l) {
+ if (lastChunkByPos != null && l == lastChunkByPos.chunkKey) {
+ return lastChunkByPos;
+ }
+ return lastChunkByPos = super.get(l);
+ }
+ // Paper end
public Chunk a(Object object) {
return this.a(((Long) object).longValue());
diff --git a/src/main/java/net/minecraft/server/ChunkProviderServer.java b/src/main/java/net/minecraft/server/ChunkProviderServer.java
index 7ac07ac07ac0..7ac07ac07ac0 100644
--- a/src/main/java/net/minecraft/server/ChunkProviderServer.java
+++ b/src/main/java/net/minecraft/server/ChunkProviderServer.java
@@ -78,15 +78,16 @@ public class ChunkProviderServer implements IChunkProvider {
Chunk chunk;
synchronized (this.chunkLoader) {
- if (this.lastChunk != null && this.lastChunk.getPos().x == i && this.lastChunk.getPos().z == j) {
+ // Paper start - remove vanilla lastChunk, we do it more accurately
+ /* if (this.lastChunk != null && this.lastChunk.locX == i && this.lastChunk.locZ == j) {
return this.lastChunk;
- }
+ }*/ // Paper end
long k = ChunkCoordIntPair.a(i, j);
chunk = (Chunk) this.chunks.get(k);
if (chunk != null) {
- this.lastChunk = chunk;
+ //this.lastChunk = chunk; // Paper remove vanilla lastChunk
return chunk;
}
@@ -198,7 +199,7 @@ public class ChunkProviderServer implements IChunkProvider {
}
this.chunks.put(k, chunk);
- this.lastChunk = chunk;
+ //this.lastChunk = chunk; // Paper
}
this.asyncTaskHandler.postToMainThread(chunk::addEntities);
@@ -343,7 +344,7 @@ public class ChunkProviderServer implements IChunkProvider {
this.saveChunk(chunk, true); // Spigot
}
this.chunks.remove(chunk.chunkKey);
- this.lastChunk = null;
+ // this.lastChunk = null; // Paper
}
return true;
}
@@ -379,6 +380,6 @@ public class ChunkProviderServer implements IChunkProvider {
}
public boolean isLoaded(int i, int j) {
- return this.chunks.containsKey(ChunkCoordIntPair.a(i, j));
+ return this.chunks.get(ChunkCoordIntPair.asLong(i, j)) != null; // Paper - use get for last access
}
}
--
2.19.1