Paper/patches/removed/1.17/0438-Workaround-for-Client-Lag-Spikes-MC-162253.patch
2021-06-15 19:34:04 +02:00

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: MeFisto94 <MeFisto94@users.noreply.github.com>
Date: Tue, 12 May 2020 23:02:43 +0200
Subject: [PATCH] Workaround for Client Lag Spikes (MC-162253)
When crossing certain chunk boundaries, the client needlessly
calculates light maps for chunk neighbours. In some specific map
configurations, these calculations cause a 500ms+ freeze on the Client.
This patch basically serves as a workaround by sending light maps
to the client, so that it doesn't attempt to calculate them.
This mitigates the frametime impact to a minimum (but it's still there).
1.17 UPDATE NOTE: More or less untested, mapped version of the patch: https://paste.gg/p/anonymous/594123c7ce7d4d398d8834af6ba386d1
diff --git a/src/main/java/net/minecraft/server/level/ChunkMap.java b/src/main/java/net/minecraft/server/level/ChunkMap.java
index d8f99f7f5ca0e1dbbb9b760af3a4b4f9c52ef6c7..f700ac973ebc3037a5a44eac3c9d505b98adce41 100644
--- a/src/main/java/net/minecraft/server/level/ChunkMap.java
+++ b/src/main/java/net/minecraft/server/level/ChunkMap.java
@@ -1906,9 +1906,68 @@ Sections go from 0..16. Now whenever a section is not empty, it can potentially
public void playerLoadedChunk(ServerPlayer player, Packet<?>[] packets, LevelChunk chunk) { // Paper - private -> public
if (packets[0] == null) {
+ // Paper start - add 8 for light fix workaround
+ if (packets.length != 10) { // in case Plugins call sendChunk, resize
+ packets = new Packet[10];
+ }
+ // Paper end
packets[0] = new ClientboundLevelChunkPacket(chunk);
packets[1] = new ClientboundLightUpdatePacket(chunk.getPos(), this.lightEngine, (BitSet) null, (BitSet) null, true);
+
+ // Paper start - Fix MC-162253
+ final int lightMask = getLightMask(chunk);
+ int i = 1;
+ for (int x = -1; x <= 1; x++) {
+ for (int z = -1; z <= 1; z++) {
+ if (x == 0 && z == 0) {
+ continue;
+ }
+
+ ++i;
+
+ if (!chunk.isNeighbourLoaded(x, z)) {
+ continue;
+ }
+
+ final LevelChunk neighbor = chunk.getRelativeNeighbourIfLoaded(x, z);
+ final int updateLightMask = lightMask & ~getCeilingLightMask(neighbor);
+
+ if (updateLightMask == 0) {
+ continue;
+ }
+
+ packets[i] = new ClientboundLightUpdatePacket(new ChunkPos(chunk.getPos().x + x, chunk.getPos().z + z), lightEngine, null, null, updateLightMask, 0, true); // TODO: This line needs updating
+ }
+ }
+ }
+
+ final int viewDistance = playerViewDistanceBroadcastMap.getLastViewDistance(player);
+ final long lastPosition = playerViewDistanceBroadcastMap.getLastCoordinate(player);
+
+ int j = 1;
+ for (int x = -1; x <= 1; x++) {
+ for (int z = -1; z <= 1; z++) {
+ if (x == 0 && z == 0) {
+ continue;
+ }
+
+ ++j;
+
+ Packet<?> packet = packets[j];
+ if (packet == null) {
+ continue;
+ }
+
+ final int distX = Math.abs(MCUtil.getCoordinateX(lastPosition) - (chunk.getPos().x + x));
+ final int distZ = Math.abs(MCUtil.getCoordinateZ(lastPosition) - (chunk.getPos().z + z));
+
+ if (Math.max(distX, distZ) > viewDistance) {
+ continue;
+ }
+ player.connection.send(packet);
+ }
}
+ // Paper end - Fix MC-162253
player.trackChunk(chunk.getPos(), packets[0], packets[1]);
DebugPackets.sendPoiPacketsForChunk(this.level, chunk.getPos());
diff --git a/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java b/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
index a63dc77db41dab79f03ef7384da55c1cdeca5d98..7cced5d06f296fcdc1209a43e7b3d1d9b47c0b26 100644
--- a/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
+++ b/src/main/java/net/minecraft/world/level/chunk/LevelChunk.java
@@ -262,7 +262,7 @@ public class LevelChunk implements ChunkAccess {
// broadcast
Object[] backingSet = inRange.getBackingSet();
- Packet[] chunkPackets = new Packet[2];
+ Packet[] chunkPackets = new Packet[10];
for (int index = 0, len = backingSet.length; index < len; ++index) {
Object temp = backingSet[index];
if (!(temp instanceof net.minecraft.server.level.ServerPlayer)) {