1 files changed, 111 insertions, 0 deletions
diff --git a/patches/server/0389-Optimize-Collision-to-not-load-chunks.patch b/patches/server/0389-Optimize-Collision-to-not-load-chunks.patch
new file mode 100644
index 0000000000..7d98711960
--- /dev/null
+++ b/patches/server/0389-Optimize-Collision-to-not-load-chunks.patch
@@ -0,0 +1,111 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Aikar <[email protected]>
+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 3c176d48e6b1a8e165b5860cd443b36c65397ce9..c909163f664875bded56656ad3c0ca6c39265abb 100644
+--- a/src/main/java/net/minecraft/server/players/PlayerList.java
++++ b/src/main/java/net/minecraft/server/players/PlayerList.java
+@@ -791,6 +791,7 @@ 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 2983a5dfc781f40f345a8ca88c83c6af44ea2c7c..03ead8423d022f91f849990b6167d86fec066361 100644
+--- a/src/main/java/net/minecraft/world/entity/Entity.java
++++ b/src/main/java/net/minecraft/world/entity/Entity.java
+@@ -174,6 +174,7 @@ public abstract class Entity implements Nameable, EntityAccess, CommandSource, i
+     // Paper end
+ 
+     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..a733c91700a38634806e9155c693b227e6aa16b6 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.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;