Paper/patches/server/0376-Optimize-Collision-to-not-load-chunks.patch
Spottedleaf 01a13871de
Rewrite chunk system (#8177)
Patch documentation to come

Issues with the old system that are fixed now:
- World generation does not scale with cpu cores effectively.
- Relies on the main thread for scheduling and maintaining chunk state, dropping chunk load/generate rates at lower tps.
- Unreliable prioritisation of chunk gen/load calls that block the main thread.
- Shutdown logic is utterly unreliable, as it has to wait for all chunks to unload - is it guaranteed that the chunk system is in a state on shutdown that it can reliably do this? Watchdog shutdown also typically failed due to thread checks, which is now resolved.
- Saving of data is not unified (i.e can save chunk data without saving entity data, poses problems for desync if shutdown is really abnormal.
- Entities are not loaded with chunks. This caused quite a bit of headache for Chunk#getEntities API, but now the new chunk system loads entities with chunks so that they are ready whenever the chunk loads in. Effectively brings the behavior back to 1.16 era, but still storing entities in their own separate regionfiles.

The above list is not complete. The patch documentation will complete it.

New chunk system hard relies on starlight and dataconverter, and most importantly the new concurrent utilities in ConcurrentUtil.

Some of the old async chunk i/o interface (i.e the old file io thread reroutes _some_ calls to the new file io thread) is kept for plugin compat reasons. It will be removed in the next major version of minecraft.

The old legacy chunk system patches have been moved to the removed folder in case we need them again.
2022-09-26 01:02:51 -07:00

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From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Thu, 2 Apr 2020 02:37:57 -0400
Subject: [PATCH] Optimize Collision to not load chunks
The collision code takes an AABB and generates a cuboid of checks rather
than a cylinder, so at high velocity this can generate a lot of chunk checks.
Treat an unloaded chunk as a collision for entities, and also for players if
the "prevent moving into unloaded chunks" setting is enabled.
If that serting is not enabled, collisions will be ignored for players, since
movement will load only the chunk the player enters anyways and avoids loading
massive amounts of surrounding chunks due to large AABB lookups.
diff --git a/src/main/java/net/minecraft/server/players/PlayerList.java b/src/main/java/net/minecraft/server/players/PlayerList.java
index 6e585b79bf2eccc6bfc98d7cdc05efea699d4e2f..78c2872ed6f696053a03e8c37995f4c2f67a9aa6 100644
--- a/src/main/java/net/minecraft/server/players/PlayerList.java
+++ b/src/main/java/net/minecraft/server/players/PlayerList.java
@@ -797,6 +797,7 @@ public abstract class PlayerList {
entityplayer1.forceSetPositionRotation(location.getX(), location.getY(), location.getZ(), location.getYaw(), location.getPitch());
// CraftBukkit end
+ worldserver1.getChunkSource().addRegionTicket(net.minecraft.server.level.TicketType.POST_TELEPORT, new net.minecraft.world.level.ChunkPos(location.getBlockX() >> 4, location.getBlockZ() >> 4), 1, entityplayer.getId()); // Paper
while (avoidSuffocation && !worldserver1.noCollision((Entity) entityplayer1) && entityplayer1.getY() < (double) worldserver1.getMaxBuildHeight()) {
entityplayer1.setPos(entityplayer1.getX(), entityplayer1.getY() + 1.0D, entityplayer1.getZ());
}
diff --git a/src/main/java/net/minecraft/world/entity/Entity.java b/src/main/java/net/minecraft/world/entity/Entity.java
index 904015183bbaa3ac3976e3d81a7968ebb18c0c41..7326d892f40447b716c93efe2f01fbbb67d6b942 100644
--- a/src/main/java/net/minecraft/world/entity/Entity.java
+++ b/src/main/java/net/minecraft/world/entity/Entity.java
@@ -236,6 +236,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource {
public org.bukkit.event.entity.CreatureSpawnEvent.SpawnReason spawnReason; // Paper
public com.destroystokyo.paper.loottable.PaperLootableInventoryData lootableData; // Paper
+ public boolean collisionLoadChunks = false; // Paper
private CraftEntity bukkitEntity;
public @org.jetbrains.annotations.Nullable net.minecraft.server.level.ChunkMap.TrackedEntity tracker; // Paper
diff --git a/src/main/java/net/minecraft/world/level/BlockCollisions.java b/src/main/java/net/minecraft/world/level/BlockCollisions.java
index 8390ce194ccc692139c0e870c16a7fb76ac8ba68..95e22c91bc701785f4804e5d4e0a6b420b9830fd 100644
--- a/src/main/java/net/minecraft/world/level/BlockCollisions.java
+++ b/src/main/java/net/minecraft/world/level/BlockCollisions.java
@@ -66,22 +66,41 @@ public class BlockCollisions extends AbstractIterator<VoxelShape> {
protected VoxelShape computeNext() {
while(true) {
if (this.cursor.advance()) {
- int i = this.cursor.nextX();
- int j = this.cursor.nextY();
- int k = this.cursor.nextZ();
+ int i = this.cursor.nextX(); final int x = i; // Paper
+ int j = this.cursor.nextY(); final int y = j; // Paper
+ int k = this.cursor.nextZ(); final int z = k; // Paper
int l = this.cursor.getNextType();
if (l == 3) {
continue;
}
+ // Paper start - ensure we don't load chunks
+ final @Nullable Entity source = this.context instanceof net.minecraft.world.phys.shapes.EntityCollisionContext entityContext ? entityContext.getEntity() : null;
+ boolean far = source != null && net.minecraft.server.MCUtil.distanceSq(source.getX(), y, source.getZ(), x, y, z) > 14;
+ this.pos.set(x, y, z);
- BlockGetter blockGetter = this.getChunk(i, k);
- if (blockGetter == null) {
+ BlockState blockState;
+ if (this.collisionGetter instanceof net.minecraft.server.level.WorldGenRegion) {
+ BlockGetter blockGetter = this.getChunk(x, z);
+ if (blockGetter == null) {
+ continue;
+ }
+ blockState = blockGetter.getBlockState(this.pos);
+ } else if ((!far && source instanceof net.minecraft.server.level.ServerPlayer) || (source != null && source.collisionLoadChunks)) {
+ blockState = this.collisionGetter.getBlockState(this.pos);
+ } else {
+ blockState = this.collisionGetter.getBlockStateIfLoaded(this.pos);
+ }
+
+ if (blockState == null) {
+ if (!(source instanceof net.minecraft.server.level.ServerPlayer) || source.level.paperConfig().chunks.preventMovingIntoUnloadedChunks) {
+ return Shapes.create(far ? source.getBoundingBox() : new AABB(new BlockPos(x, y, z)));
+ }
+ // Paper end
continue;
}
- this.pos.set(i, j, k);
- BlockState blockState = blockGetter.getBlockState(this.pos);
- if (this.onlySuffocatingBlocks && !blockState.isSuffocating(blockGetter, this.pos) || l == 1 && !blockState.hasLargeCollisionShape() || l == 2 && !blockState.is(Blocks.MOVING_PISTON)) {
+ // Paper - moved up
+ if (/*this.onlySuffocatingBlocks && (!blockState.isSuffocating(blockGetter, this.pos)) ||*/ l == 1 && !blockState.hasLargeCollisionShape() || l == 2 && !blockState.is(Blocks.MOVING_PISTON)) { // Paper - onlySuffocatingBlocks is only true on the client, so we don't care about it here
continue;
}
diff --git a/src/main/java/net/minecraft/world/level/CollisionGetter.java b/src/main/java/net/minecraft/world/level/CollisionGetter.java
index 4c373d6c8ddd9f5db88888cd8dbbfc24eb5df793..56d94c94fb0d4dc468bb5d69be655ddd5c6b5360 100644
--- a/src/main/java/net/minecraft/world/level/CollisionGetter.java
+++ b/src/main/java/net/minecraft/world/level/CollisionGetter.java
@@ -44,11 +44,13 @@ public interface CollisionGetter extends BlockGetter {
}
default boolean noCollision(@Nullable Entity entity, AABB box) {
+ try { if (entity != null) entity.collisionLoadChunks = true; // Paper
for(VoxelShape voxelShape : this.getBlockCollisions(entity, box)) {
if (!voxelShape.isEmpty()) {
return false;
}
}
+ } finally { if (entity != null) entity.collisionLoadChunks = false; } // Paper
if (!this.getEntityCollisions(entity, box).isEmpty()) {
return false;