PaperMC/Spigot-Server-Patches/0518-Optimize-Pathfinder-Remove-Streams-Optimized-collect.patch

From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: Aikar <aikar@aikar.co>
Date: Mon, 11 May 2020 04:18:54 -0400
Subject: [PATCH] Optimize Pathfinder - Remove Streams / Optimized collections

I utilized the IDE to convert streams to non streams code, so shouldn't
be any risk of behavior change. Only did minor optimization of the
generated code set to remove unnecessary things.

I expect us to just drop this patch on next major update and re-apply
it with the IDE again and re-apply the collections optimization.

Optimize collection by creating a list instead of a set of the key and value.

This lets us get faster foreach iteration, as well as avoids map lookups on
the values when needed.

diff --git a/src/main/java/net/minecraft/server/Pathfinder.java b/src/main/java/net/minecraft/server/Pathfinder.java
index 67c63cfe333e328cbd00ada970bd81efebfe30b6..71b96943d865105f279dda613b7ac6b3ffed793b 100644
--- a/src/main/java/net/minecraft/server/Pathfinder.java
+++ b/src/main/java/net/minecraft/server/Pathfinder.java
@@ -31,9 +31,15 @@ public class Pathfinder {
         this.a.a();
         this.e.a(chunkcache, entityinsentient);
         PathPoint pathpoint = this.e.b();
-        Map<PathDestination, BlockPosition> map = (Map) set.stream().collect(Collectors.toMap((blockposition) -> {
-            return this.e.a((double) blockposition.getX(), (double) blockposition.getY(), (double) blockposition.getZ());
-        }, Function.identity()));
+        // Paper start - remove streams - and optimize collection
+        List<Map.Entry<PathDestination, BlockPosition>> map = new java.util.ArrayList<>();
+        for (BlockPosition blockposition : set) {
+            // cast is important
+            //noinspection RedundantCast
+            PathDestination path = this.e.a((double) blockposition.getX(), (double) blockposition.getY(), (double) blockposition.getZ());
+            map.add(new java.util.AbstractMap.SimpleEntry<>(path, blockposition));
+        }
+        // Paper end
         PathEntity pathentity = this.a(pathpoint, map, f, i, f1);
 
         this.e.a();
@@ -41,11 +47,11 @@ public class Pathfinder {
     }
 
     @Nullable
-    private PathEntity a(PathPoint pathpoint, Map<PathDestination, BlockPosition> map, float f, int i, float f1) {
-        Set<PathDestination> set = map.keySet();
+    private PathEntity a(PathPoint pathpoint, java.util.List<java.util.Map.Entry<PathDestination, BlockPosition>> list, float f, int i, float f1) { // Paper - list instead of set
+        //Set<PathDestination> set = map.keySet(); // Paper
 
         pathpoint.e = 0.0F;
-        pathpoint.f = this.a(pathpoint, set);
+        pathpoint.f = this.a(pathpoint, list); // Paper - list instead of map
         pathpoint.g = pathpoint.f;
         this.a.a();
         this.b.clear();
@@ -62,10 +68,23 @@ public class Pathfinder {
             PathPoint pathpoint1 = this.a.c();
 
             pathpoint1.i = true;
-            set.stream().filter((pathdestination) -> {
-                return pathpoint1.c((PathPoint) pathdestination) <= (float) i;
-            }).forEach(PathDestination::e);
-            if (set.stream().anyMatch(PathDestination::f)) {
+            // Paper start - remove streams
+            for (int i1 = 0, listSize = list.size(); i1 < listSize; i1++) {
+                PathDestination pathdestination = list.get(i1).getKey();
+                if (pathpoint1.c(pathdestination) <= (float) i) {
+                    pathdestination.e();
+                }
+            }
+            boolean result = false;
+            for (int i1 = 0, listSize = list.size(); i1 < listSize; i1++) {
+                PathDestination pathdestination = list.get(i1).getKey();
+                if (pathdestination.f()) {
+                    result = true;
+                    break;
+                }
+            }
+            if (result) {
+                // Paper end
                 break;
             }
 
@@ -82,7 +101,7 @@ public class Pathfinder {
                     if (pathpoint2.j < f && (!pathpoint2.c() || f3 < pathpoint2.e)) {
                         pathpoint2.h = pathpoint1;
                         pathpoint2.e = f3;
-                        pathpoint2.f = this.a(pathpoint2, set) * 1.5F;
+                        pathpoint2.f = this.a(pathpoint2, list) * 1.5F; // Paper - use list instead of map
                         if (pathpoint2.c()) {
                             this.a.a(pathpoint2, pathpoint2.e + pathpoint2.f);
                         } else {
@@ -94,36 +113,49 @@ public class Pathfinder {
             }
         }
 
-        Stream stream;
 
-        if (set.stream().anyMatch(PathDestination::f)) {
-            stream = set.stream().filter(PathDestination::f).map((pathdestination) -> {
-                return this.a(pathdestination.d(), (BlockPosition) map.get(pathdestination), true);
-            }).sorted(Comparator.comparingInt(PathEntity::e));
-        } else {
-            stream = set.stream().map((pathdestination) -> {
-                return this.a(pathdestination.d(), (BlockPosition) map.get(pathdestination), false);
-            }).sorted(Comparator.comparingDouble(PathEntity::l).thenComparingInt(PathEntity::e));
+        // Paper start - remove streams
+        boolean result = false;
+        for (int i1 = 0, listSize = list.size(); i1 < listSize; i1++) {
+            PathDestination pathDestination = list.get(i1).getKey(); // Paper
+            if (pathDestination.f()) {
+                result = true;
+                break;
+            }
         }
-
-        Optional<PathEntity> optional = stream.findFirst();
-
-        if (!optional.isPresent()) {
-            return null;
+        List<PathEntity> candidates = new java.util.ArrayList<>();
+        if (result) {
+            for (int i1 = 0, listSize = list.size(); i1 < listSize; i1++) {
+                Map.Entry<PathDestination, BlockPosition> entry = list.get(i1);
+                PathDestination pathdestination = entry.getKey();
+                if (pathdestination.f()) {
+                    PathEntity pathEntity = this.a(pathdestination.d(), entry.getValue(), true);
+                    candidates.add(pathEntity);
+                }
+            }
+            if (candidates.isEmpty()) return null;
+            candidates.sort(Comparator.comparingInt(PathEntity::e));
         } else {
-            PathEntity pathentity = (PathEntity) optional.get();
-
-            return pathentity;
+            for (int i1 = 0, listSize = list.size(); i1 < listSize; i1++) {
+                Map.Entry<PathDestination, BlockPosition> entry = list.get(i1);
+                PathDestination pathdestination = entry.getKey();
+                PathEntity pathEntity = this.a(pathdestination.d(), entry.getValue(), false);
+                candidates.add(pathEntity);
+            }
+            if (candidates.isEmpty()) return null;
+            candidates.sort(Comparator.comparingDouble(PathEntity::l).thenComparingInt(PathEntity::e));
         }
+        return candidates.get(0);
+        // Paper end
     }
 
-    private float a(PathPoint pathpoint, Set<PathDestination> set) {
+    private float a(PathPoint pathpoint, java.util.List<java.util.Map.Entry<PathDestination, BlockPosition>> list) {
         float f = Float.MAX_VALUE;
 
         float f1;
 
-        for (Iterator iterator = set.iterator(); iterator.hasNext(); f = Math.min(f1, f)) {
-            PathDestination pathdestination = (PathDestination) iterator.next();
+        for (int i = 0, listSize = list.size(); i < listSize; f = Math.min(f1, f), i++) { // Paper
+            PathDestination pathdestination = list.get(i).getKey(); // Paper
 
             f1 = pathpoint.a(pathdestination);
             pathdestination.a(f1, pathpoint);