PaperMC/patches/server-remapped/0678-Remove-streams-from-SensorNearest.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Bjarne Koll <lynxplay101@gmail.com>
Date: Wed, 3 Mar 2021 12:48:48 +0100
Subject: [PATCH] Remove streams from SensorNearest

The behavioural nearby sensors are validated every tick on the entities
that registered the respective sensors and are therefore a good subject
to performance improvements.

More specifically this commit replaces the Stream#filter usage with
ArrayList#removeIf as the removeIf method on an array list is heavily
optimized towards a single internal array re-allocation without any
further overhead on the removeIf call.

The only negative of this change is the rather agressive diff these
patches introduce as the methods are basically being reimplemented
compared to the previous stream-based implementation.

See: https://nipafx.dev/java-stream-performance/

diff --git a/src/main/java/net/minecraft/world/entity/ai/sensing/NearestItemSensor.java b/src/main/java/net/minecraft/world/entity/ai/sensing/NearestItemSensor.java
index 91295b8501b1e9d60bf9a7e954ea7fbce9cdea7f..0cd5a19beeb6103dec454b9071cc2e40adf2d006 100644
--- a/src/main/java/net/minecraft/world/entity/ai/sensing/NearestItemSensor.java
+++ b/src/main/java/net/minecraft/world/entity/ai/sensing/NearestItemSensor.java
@@ -27,18 +27,16 @@ public class NearestItemSensor extends Sensor<Mob> {
         List<ItemEntity> list = world.getEntitiesOfClass(ItemEntity.class, entity.getBoundingBox().inflate(8.0D, 4.0D, 8.0D), (entityitem) -> {
             return true;
         });
-
-        entity.getClass();
+        // Paper start - remove streams in favour of lists
         list.sort(Comparator.comparingDouble(entity::distanceToSqr));
-        Stream stream = list.stream().filter((entityitem) -> {
-            return entity.wantsToPickUp(entityitem.getItem());
-        }).filter((entityitem) -> {
-            return entityitem.closerThan((Entity) entity, 9.0D);
-        });
-
-        entity.getClass();
-        Optional<ItemEntity> optional = stream.filter(entity::hasLineOfSight).findFirst();
-
-        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_VISIBLE_WANTED_ITEM, optional);
+        ItemEntity nearest = null;
+        for (ItemEntity entityItem : list) {
+            if (entity.wantsToPickUp(entityItem.getItem()) && entityItem.closerThan(entity, 9.0D) && entity.canSee(entityItem)) {
+                nearest = entityItem;
+                break;
+            }
+        }
+        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_VISIBLE_WANTED_ITEM, Optional.ofNullable(nearest));
+        // Paper end
     }
 }
diff --git a/src/main/java/net/minecraft/world/entity/ai/sensing/NearestLivingEntitySensor.java b/src/main/java/net/minecraft/world/entity/ai/sensing/NearestLivingEntitySensor.java
index bf38e8b465ae0f50e34b94e0d7830dfdc1be1d59..fa827377ef0ef7cb280d1d54e156e45579899e6c 100644
--- a/src/main/java/net/minecraft/world/entity/ai/sensing/NearestLivingEntitySensor.java
+++ b/src/main/java/net/minecraft/world/entity/ai/sensing/NearestLivingEntitySensor.java
@@ -26,10 +26,12 @@ public class NearestLivingEntitySensor extends Sensor<LivingEntity> {
         list.sort(Comparator.comparingDouble(entity::distanceToSqr));
         Brain<?> behaviorcontroller = entity.getBrain();
 
-        behaviorcontroller.setMemory(MemoryModuleType.MOBS, (Object) list);
-        behaviorcontroller.setMemory(MemoryModuleType.VISIBLE_MOBS, list.stream().filter((entityliving1) -> {
-            return doTick(entity, entityliving1);
-        }).collect(Collectors.toList()));
+        behaviorcontroller.setMemory(MemoryModuleType.MOBS, list); // Paper - decompile error
+        // Paper start - remove streams in favour of lists
+        List<LivingEntity> visibleMobs = new java.util.ArrayList<>(list);
+        visibleMobs.removeIf(otherEntityLiving -> !Sensor.a(entity, otherEntityLiving));
+        behaviorcontroller.setMemory(MemoryModuleType.VISIBLE_MOBS, visibleMobs);
+        // Paper end
     }
 
     @Override
diff --git a/src/main/java/net/minecraft/world/entity/ai/sensing/PlayerSensor.java b/src/main/java/net/minecraft/world/entity/ai/sensing/PlayerSensor.java
index 41a9db2cc4af26baa7072b3c4cebc5357ff43301..fe7414293f144656a938de42524841592c9f40d4 100644
--- a/src/main/java/net/minecraft/world/entity/ai/sensing/PlayerSensor.java
+++ b/src/main/java/net/minecraft/world/entity/ai/sensing/PlayerSensor.java
@@ -26,22 +26,26 @@ public class PlayerSensor extends Sensor<LivingEntity> {
 
     @Override
     protected void doTick(ServerLevel world, LivingEntity entity) {
-        Stream stream = world.players().stream().filter(EntitySelector.NO_SPECTATORS).filter((entityplayer) -> {
-            return entity.closerThan((Entity) entityplayer, 16.0D);
-        });
+        // Paper start - remove streams in favour of lists
+        List<Player> players = new java.util.ArrayList<>(world.players());
+        players.removeIf(player -> !EntitySelector.notSpectator().test(player) || !entity.closerThan(player, 16.0D)); // Paper - removeIf only re-allocates once compared to iterator
+        players.sort(Comparator.comparingDouble(entity::distanceToSqr));
 
-        entity.getClass();
-        List<Player> list = (List) stream.sorted(Comparator.comparingDouble(entity::h)).collect(Collectors.toList());
         Brain<?> behaviorcontroller = entity.getBrain();
-
-        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_PLAYERS, (Object) list);
-        List<Player> list1 = (List) list.stream().filter((entityhuman) -> {
-            return doTick(entity, (LivingEntity) entityhuman);
-        }).collect(Collectors.toList());
-
-        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_VISIBLE_PLAYER, (Object) (list1.isEmpty() ? null : (Player) list1.get(0)));
-        Optional<Player> optional = list1.stream().filter(EntitySelector.ATTACK_ALLOWED).findFirst();
-
-        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_VISIBLE_TARGETABLE_PLAYER, optional);
+        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_PLAYERS, players);
+
+        Player nearest = null, nearestTargetable = null;
+        for (Player player : players) {
+            if (Sensor.a(entity, player)) {
+                if (nearest == null) nearest = player;
+                if (EntitySelector.canAITarget().test(player)) {
+                    nearestTargetable = player;
+                    break; // Both variables are assigned, no reason to loop further
+                }
+            }
+        }
+        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_VISIBLE_PLAYER, nearest);
+        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_VISIBLE_TARGETABLE_PLAYER, nearestTargetable);
+        // Paper end
     }
 }