PaperMC/Spigot-Server-Patches/0680-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/server/SensorNearestItems.java b/src/main/java/net/minecraft/server/SensorNearestItems.java
index 2e747158d48ab28ac1611990cc97aa4a9e30b30e..edf7d31e8e06f67be58282b2a76d1ac899b4f3e8 100644
--- a/src/main/java/net/minecraft/server/SensorNearestItems.java
+++ b/src/main/java/net/minecraft/server/SensorNearestItems.java
@@ -21,18 +21,16 @@ 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/server/SensorNearestLivingEntities.java b/src/main/java/net/minecraft/server/SensorNearestLivingEntities.java
index f6568a54ab85bc3a682f6fbb19dda7a783625bbe..b3388d4a665e8f91083a2e746482a9f0bd988da1 100644
--- a/src/main/java/net/minecraft/server/SensorNearestLivingEntities.java
+++ b/src/main/java/net/minecraft/server/SensorNearestLivingEntities.java
@@ -21,10 +21,12 @@ 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/server/SensorNearestPlayers.java b/src/main/java/net/minecraft/server/SensorNearestPlayers.java
index 904a6d5ac61d2ac81f1057068383e9ab432852db..ae946619f10a757171e4217e414d6a5248a45494 100644
--- a/src/main/java/net/minecraft/server/SensorNearestPlayers.java
+++ b/src/main/java/net/minecraft/server/SensorNearestPlayers.java
@@ -19,22 +19,26 @@ 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
     }
 }