Remove some Streams usage in Entity Collision

While there is more down the collision system, remove some of the wrapping
Spliterator stuff as even this wrapper stream has shown up in profiling.

With other collision optimizations, we might also even avoid inner streams too.

Spigot-Server-Patches/0453-Optimize-Collision-to-not-load-chunks.patch

@@ -14,10 +14,10 @@ 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/ICollisionAccess.java b/src/main/java/net/minecraft/server/ICollisionAccess.java
-index f851ed11df14fd9aa8017f44d82fb6cfc3bde345..d9aeb27a3d6cc2fef2030eafd01d92ef7758111c 100644
+index f851ed11df14fd9aa8017f44d82fb6cfc3bde345..bdebbaf0b93ae7186b0afb3b2c04fdcf11148121 100644
 --- a/src/main/java/net/minecraft/server/ICollisionAccess.java
 +++ b/src/main/java/net/minecraft/server/ICollisionAccess.java
-@@ -83,19 +83,28 @@ public interface ICollisionAccess extends IBlockAccess {
+@@ -83,19 +83,29 @@ public interface ICollisionAccess extends IBlockAccess {
                  }
  
                  while (cursorposition.a()) {
@@ -40,12 +40,13 @@ index f851ed11df14fd9aa8017f44d82fb6cfc3bde345..d9aeb27a3d6cc2fef2030eafd01d92ef
 +                        // Paper start - ensure we don't load chunks
 +                        //int k2 = k1 >> 4;
 +                        //int l2 = i2 >> 4;
-+                        //boolean far = entity != null && MCUtil.distance(entity.locX(), entity.locY(), entity.locZ(), x, y, z) > 8;
++                        boolean far = entity != null && MCUtil.distance(entity.locX(), entity.locY(), entity.locZ(), x, y, z) > 1;
 +                        blockposition_mutableblockposition.setValues(x, y, z); // Paper - moved up
++
 +                        IBlockData iblockdata = ICollisionAccess.this.getTypeIfLoaded(blockposition_mutableblockposition);
 +                        if (iblockdata == null) {
 +                            if (!(entity instanceof EntityPlayer) || entity.world.paperConfig.preventMovingIntoUnloadedChunks) {
-+                                VoxelShape voxelshape3 = VoxelShapes.a(new AxisAlignedBB(new BlockPosition(x, y, z)));
++                                VoxelShape voxelshape3 = VoxelShapes.of(far ? entity.getBoundingBox() : new AxisAlignedBB(new BlockPosition(x, y, z)));
 +                                consumer.accept(voxelshape3);
 +                                return true;
 +                            }

Spigot-Server-Patches/0512-Implement-JellySquid-s-Entity-Collision-optimisation.patch

@@ -9,10 +9,10 @@ Original code by JellySquid, licensed under GNU Lesser General Public License v3
 you can find the original code on https://github.com/jellysquid3/lithium-fabric/tree/1.15.x/fabric (Yarn mappings)
 
 diff --git a/src/main/java/net/minecraft/server/ICollisionAccess.java b/src/main/java/net/minecraft/server/ICollisionAccess.java
-index d9aeb27a3d6cc2fef2030eafd01d92ef7758111c..67c3f0fc718089bb1f57bbb45fda5677bd628cbd 100644
+index bdebbaf0b93ae7186b0afb3b2c04fdcf11148121..be4e311eadbd5a3b4d17ec6eb691d3ff0af711ae 100644
 --- a/src/main/java/net/minecraft/server/ICollisionAccess.java
 +++ b/src/main/java/net/minecraft/server/ICollisionAccess.java
-@@ -108,11 +108,24 @@ public interface ICollisionAccess extends IBlockAccess {
+@@ -109,11 +109,24 @@ public interface ICollisionAccess extends IBlockAccess {
  
                              if ((j2 != 1 || iblockdata.f()) && (j2 != 2 || iblockdata.getBlock() == Blocks.MOVING_PISTON)) {
                                  VoxelShape voxelshape2 = iblockdata.b((IBlockAccess) ICollisionAccess.this, blockposition_mutableblockposition, voxelshapecollision);

Spigot-Server-Patches/0513-Remove-some-Streams-usage-in-Entity-Collision.patch

@@ -0,0 +1,177 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Aikar <aikar@aikar.co>
+Date: Sat, 9 May 2020 18:36:27 -0400
+Subject: [PATCH] Remove some Streams usage in Entity Collision
+
+While there is more down the collision system, remove some of the wrapping
+Spliterator stuff as even this wrapper stream has shown up in profiling.
+
+With other collision optimizations, we might also even avoid inner streams too.
+
+diff --git a/src/main/java/net/minecraft/server/GeneratorAccess.java b/src/main/java/net/minecraft/server/GeneratorAccess.java
+index e865a5694f78fb9273a0625ab2c30b87d0711a90..5648ba73c533f622c35c808decdb305f8a1cf6b0 100644
+--- a/src/main/java/net/minecraft/server/GeneratorAccess.java
++++ b/src/main/java/net/minecraft/server/GeneratorAccess.java
+@@ -52,6 +52,7 @@ public interface GeneratorAccess extends IEntityAccess, IWorldReader, VirtualLev
+         this.a((EntityHuman) null, i, blockposition, j);
+     }
+ 
++    @Override default java.util.List<VoxelShape> getEntityCollisions(@Nullable Entity entity, AxisAlignedBB axisalignedbb, Set<Entity> set, boolean returnFast) {return IEntityAccess.super.getEntityCollisions(entity, axisalignedbb, set, returnFast); } // Paper
+     @Override
+     default Stream<VoxelShape> b(@Nullable Entity entity, AxisAlignedBB axisalignedbb, Set<Entity> set) {
+         return IEntityAccess.super.b(entity, axisalignedbb, set);
+diff --git a/src/main/java/net/minecraft/server/ICollisionAccess.java b/src/main/java/net/minecraft/server/ICollisionAccess.java
+index be4e311eadbd5a3b4d17ec6eb691d3ff0af711ae..434d8fd019b63e7352c435fe72cdfc32e338e8c5 100644
+--- a/src/main/java/net/minecraft/server/ICollisionAccess.java
++++ b/src/main/java/net/minecraft/server/ICollisionAccess.java
+@@ -43,18 +43,39 @@ public interface ICollisionAccess extends IBlockAccess {
+     }
+ 
+     default boolean a(@Nullable Entity entity, AxisAlignedBB axisalignedbb, Set<Entity> set) {
+-        return this.c(entity, axisalignedbb, set).allMatch(VoxelShape::isEmpty);
++        // Paper start - reduce stream usage
++        java.util.List<VoxelShape> blockCollisions = getBlockCollision(entity, axisalignedbb, true);
++        for (int i = 0; i < blockCollisions.size(); i++) {
++            VoxelShape blockCollision = blockCollisions.get(i);
++            if (!blockCollision.isEmpty()) {
++                return false;
++            }
++        }
++        return getEntityCollisions(entity, axisalignedbb, set, true).isEmpty();
++        // Paper end
+     }
+ 
++    default java.util.List<VoxelShape> getEntityCollisions(@Nullable Entity entity, AxisAlignedBB axisalignedbb, Set<Entity> set, boolean returnFast) { return java.util.Collections.emptyList(); } // Paper
+     default Stream<VoxelShape> b(@Nullable Entity entity, AxisAlignedBB axisalignedbb, Set<Entity> set) {
+         return Stream.empty();
+     }
+ 
+     default Stream<VoxelShape> c(@Nullable Entity entity, AxisAlignedBB axisalignedbb, Set<Entity> set) {
+-        return Streams.concat(new Stream[]{this.b(entity, axisalignedbb), this.b(entity, axisalignedbb, set)});
++        // Paper start - reduce stream usage
++        java.util.List<VoxelShape> blockCollisions = getBlockCollision(entity, axisalignedbb, false);
++        java.util.List<VoxelShape> entityCollisions = getEntityCollisions(entity, axisalignedbb, set, false);
++        return Stream.concat(blockCollisions.stream(), entityCollisions.stream());
++        // Paper end
+     }
+ 
+     default Stream<VoxelShape> b(@Nullable final Entity entity, AxisAlignedBB axisalignedbb) {
++        // Paper start - reduce stream usage
++        java.util.List<VoxelShape> collision = getBlockCollision(entity, axisalignedbb, false);
++        return !collision.isEmpty() ? collision.stream() : Stream.empty();
++    }
++
++    default java.util.List<VoxelShape> getBlockCollision(@Nullable final Entity entity, AxisAlignedBB axisalignedbb, boolean returnFast) {
++        // Paper end
+         int i = MathHelper.floor(axisalignedbb.minX - 1.0E-7D) - 1;
+         int j = MathHelper.floor(axisalignedbb.maxX + 1.0E-7D) + 1;
+         int k = MathHelper.floor(axisalignedbb.minY - 1.0E-7D) - 1;
+@@ -66,19 +87,19 @@ public interface ICollisionAccess extends IBlockAccess {
+         final BlockPosition.MutableBlockPosition blockposition_mutableblockposition = new BlockPosition.MutableBlockPosition();
+         final VoxelShape voxelshape = VoxelShapes.a(axisalignedbb);
+ 
+-        return StreamSupport.stream(new AbstractSpliterator<VoxelShape>(Long.MAX_VALUE, 1280) {
+-            boolean a = entity == null;
+-
+-            public boolean tryAdvance(Consumer<? super VoxelShape> consumer) {
+-                if (!this.a) {
+-                    this.a = true;
++        // Paper start - reduce stream usage (this part done by Aikar)
++        java.util.List<VoxelShape> collisions = new java.util.ArrayList<>();
++        if (true) {//return StreamSupport.stream(new AbstractSpliterator<VoxelShape>(Long.MAX_VALUE, 1280) {
++            if (true) { //public boolean tryAdvance(Consumer<? super VoxelShape> consumer) {*/ // Paper
++                if (entity != null) {
++                    // Paper end
+                     VoxelShape voxelshape1 = ICollisionAccess.this.getWorldBorder().a();
+                     boolean flag = VoxelShapes.c(voxelshape1, VoxelShapes.a(entity.getBoundingBox().shrink(1.0E-7D)), OperatorBoolean.AND);
+                     boolean flag1 = VoxelShapes.c(voxelshape1, VoxelShapes.a(entity.getBoundingBox().g(1.0E-7D)), OperatorBoolean.AND);
+ 
+                     if (!flag && flag1) {
+-                        consumer.accept(voxelshape1);
+-                        return true;
++                        collisions.add(voxelshape1);// Paper
++                        if (returnFast) return collisions;
+                     }
+                 }
+ 
+@@ -98,9 +119,8 @@ public interface ICollisionAccess extends IBlockAccess {
+                         IBlockData iblockdata = ICollisionAccess.this.getTypeIfLoaded(blockposition_mutableblockposition);
+                         if (iblockdata == null) {
+                             if (!(entity instanceof EntityPlayer) || entity.world.paperConfig.preventMovingIntoUnloadedChunks) {
+-                                VoxelShape voxelshape3 = VoxelShapes.of(far ? entity.getBoundingBox() : new AxisAlignedBB(new BlockPosition(x, y, z)));
+-                                consumer.accept(voxelshape3);
+-                                return true;
++                                collisions.add(VoxelShapes.of(far ? entity.getBoundingBox() : new AxisAlignedBB(new BlockPosition(x, y, z))));
++                                if (returnFast) return collisions;
+                             }
+                         } else {
+                             //blockposition_mutableblockposition.d(k1, l1, i2); // moved up
+@@ -117,14 +137,14 @@ public interface ICollisionAccess extends IBlockAccess {
+ 
+                                 if (voxelshape2 == VoxelShapes.fullCube()) {
+                                     if (axisalignedbb.intersects(x, y, z, x + 1.0D, y + 1.0D, z + 1.0D)) {
+-                                        consumer.accept(voxelshape2.offset(x, y, z));
+-                                        return true;
++                                        collisions.add(voxelshape2.offset(x, y, z));
++                                        if (returnFast) return collisions;
+                                     }
+                                 } else {
+                                     VoxelShape shape = voxelshape2.offset(x, y, z);
+                                     if (VoxelShapes.applyOperation(shape, voxelshape, OperatorBoolean.AND)) {
+-                                        consumer.accept(shape);
+-                                        return true;
++                                        collisions.add(shape);
++                                        if (returnFast) return collisions;
+                                     }
+                                     // Paper end
+                                 }
+@@ -133,8 +153,9 @@ public interface ICollisionAccess extends IBlockAccess {
+                     }
+                 }
+ 
+-                return false;
++                //return false; // Paper
+             }
+-        }, false);
++        } //}, false);
++        return collisions; // Paper
+     }
+ }
+diff --git a/src/main/java/net/minecraft/server/IEntityAccess.java b/src/main/java/net/minecraft/server/IEntityAccess.java
+index d434aaaaf0ab6a18ab0fe5ad0bf8ed4662f49120..3bc57ef91d557383178533b0cc87a71a521d6b3e 100644
+--- a/src/main/java/net/minecraft/server/IEntityAccess.java
++++ b/src/main/java/net/minecraft/server/IEntityAccess.java
+@@ -55,8 +55,10 @@ public interface IEntityAccess {
+         // Paper start - remove streams from entity collision
+         if (axisalignedbb.getAverageSideLength() < 1.0E-7D) {
+             return Stream.empty();
+-
+         }
++        return getEntityCollisions(entity, axisalignedbb, set, false).stream();
++    }
++    default List<VoxelShape> getEntityCollisions(@Nullable Entity entity, AxisAlignedBB axisalignedbb, Set<Entity> set, boolean returnFast) {
+         AxisAlignedBB selection = axisalignedbb.grow(1.0E-7D);
+         List<Entity> entities = entity != null && entity.hardCollides() ? getEntities(entity, selection) : getHardCollidingEntities(entity, selection);
+         List<VoxelShape> shapes = new java.util.ArrayList<>();
+@@ -74,6 +76,7 @@ public interface IEntityAccess {
+ 
+             if (otherEntityBox != null && selection.intersects(otherEntityBox)) {
+                 shapes.add(VoxelShapes.of(otherEntityBox));
++                if (returnFast) return shapes;
+             }
+ 
+             if (entity != null) {
+@@ -81,11 +84,12 @@ public interface IEntityAccess {
+ 
+                 if (otherEntityHardBox != null && selection.intersects(otherEntityHardBox)) {
+                     shapes.add(VoxelShapes.of(otherEntityHardBox));
++                    if (returnFast) return shapes;
+                 }
+             }
+         }
+ 
+-        return shapes.stream();
++        return shapes;
+         // Paper end
+     }
+