PaperMC/Spigot-Server-Patches/0676-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/SensorNearestItems.java b/src/main/java/net/minecraft/world/entity/ai/sensing/SensorNearestItems.java
index 418cd6d8b40d35aa3be73eb12f2e3b75597238b9..2e3149a0b15299468079796bd3ea56eabdb4998c 100644
--- a/src/main/java/net/minecraft/world/entity/ai/sensing/SensorNearestItems.java
+++ b/src/main/java/net/minecraft/world/entity/ai/sensing/SensorNearestItems.java
@@ -27,18 +27,16 @@ public class SensorNearestItems extends Sensor<EntityInsentient> {
         List<EntityItem> list = worldserver.a(EntityItem.class, entityinsentient.getBoundingBox().grow(8.0D, 4.0D, 8.0D), (entityitem) -> {
             return true;
         });
-
-        entityinsentient.getClass();
+        // Paper start - remove streams in favour of lists
         list.sort(Comparator.comparingDouble(entityinsentient::h));
-        Stream stream = list.stream().filter((entityitem) -> {
-            return entityinsentient.i(entityitem.getItemStack());
-        }).filter((entityitem) -> {
-            return entityitem.a((Entity) entityinsentient, 9.0D);
-        });
-
-        entityinsentient.getClass();
-        Optional<EntityItem> optional = stream.filter(entityinsentient::hasLineOfSight).findFirst();
-
-        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_VISIBLE_WANTED_ITEM, optional);
+        EntityItem nearest = null;
+        for (EntityItem entityItem : list) {
+            if (entityinsentient.i(entityItem.getItemStack()) && entityItem.a(entityinsentient, 9.0D) && entityinsentient.hasLineOfSight(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/SensorNearestLivingEntities.java b/src/main/java/net/minecraft/world/entity/ai/sensing/SensorNearestLivingEntities.java
index d3bb1c02d80fcd3586030b07f84e7ebdd97d873e..0bc17d148e91277efdf72541e5470fa56d455670 100644
--- a/src/main/java/net/minecraft/world/entity/ai/sensing/SensorNearestLivingEntities.java
+++ b/src/main/java/net/minecraft/world/entity/ai/sensing/SensorNearestLivingEntities.java
@@ -26,10 +26,12 @@ public class SensorNearestLivingEntities extends Sensor<EntityLiving> {
         list.sort(Comparator.comparingDouble(entityliving::h));
         BehaviorController<?> behaviorcontroller = entityliving.getBehaviorController();
 
-        behaviorcontroller.setMemory(MemoryModuleType.MOBS, (Object) list);
-        behaviorcontroller.setMemory(MemoryModuleType.VISIBLE_MOBS, list.stream().filter((entityliving1) -> {
-            return a(entityliving, entityliving1);
-        }).collect(Collectors.toList()));
+        behaviorcontroller.setMemory(MemoryModuleType.MOBS, list); // Paper - decompile error
+        // Paper start - remove streams in favour of lists
+        List<EntityLiving> visibleMobs = new java.util.ArrayList<>(list);
+        visibleMobs.removeIf(otherEntityLiving -> !Sensor.a(entityliving, otherEntityLiving));
+        behaviorcontroller.setMemory(MemoryModuleType.VISIBLE_MOBS, visibleMobs);
+        // Paper end
     }
 
     @Override
diff --git a/src/main/java/net/minecraft/world/entity/ai/sensing/SensorNearestPlayers.java b/src/main/java/net/minecraft/world/entity/ai/sensing/SensorNearestPlayers.java
index 29abc7feec5358dce7d16958f0c5807f4bda992f..60e4da9217d4d950b5077baf6b50eaee20f8df09 100644
--- a/src/main/java/net/minecraft/world/entity/ai/sensing/SensorNearestPlayers.java
+++ b/src/main/java/net/minecraft/world/entity/ai/sensing/SensorNearestPlayers.java
@@ -26,22 +26,26 @@ public class SensorNearestPlayers extends Sensor<EntityLiving> {
 
     @Override
     protected void a(WorldServer worldserver, EntityLiving entityliving) {
-        Stream stream = worldserver.getPlayers().stream().filter(IEntitySelector.g).filter((entityplayer) -> {
-            return entityliving.a((Entity) entityplayer, 16.0D);
-        });
+        // Paper start - remove streams in favour of lists
+        List<EntityHuman> players = new java.util.ArrayList<>(worldserver.getPlayers());
+        players.removeIf(player -> !IEntitySelector.notSpectator().test(player) || !entityliving.a(player, 16.0D)); // Paper - removeIf only re-allocates once compared to iterator
+        players.sort(Comparator.comparingDouble(entityliving::h));
 
-        entityliving.getClass();
-        List<EntityHuman> list = (List) stream.sorted(Comparator.comparingDouble(entityliving::h)).collect(Collectors.toList());
         BehaviorController<?> behaviorcontroller = entityliving.getBehaviorController();
-
-        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_PLAYERS, (Object) list);
-        List<EntityHuman> list1 = (List) list.stream().filter((entityhuman) -> {
-            return a(entityliving, (EntityLiving) entityhuman);
-        }).collect(Collectors.toList());
-
-        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_VISIBLE_PLAYER, (Object) (list1.isEmpty() ? null : (EntityHuman) list1.get(0)));
-        Optional<EntityHuman> optional = list1.stream().filter(IEntitySelector.f).findFirst();
-
-        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_VISIBLE_TARGETABLE_PLAYER, optional);
+        behaviorcontroller.setMemory(MemoryModuleType.NEAREST_PLAYERS, players);
+
+        EntityHuman nearest = null, nearestTargetable = null;
+        for (EntityHuman player : players) {
+            if (Sensor.a(entityliving, player)) {
+                if (nearest == null) nearest = player;
+                if (IEntitySelector.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
     }
 }