From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
From: JRoy <joshroy126@gmail.com>
Date: Mon, 29 Jun 2020 17:03:06 -0400
Subject: [PATCH] Remove some streams from structures

This showed up a lot in the spark profiler, should have a low-medium performance improvement.

diff --git a/src/main/java/net/minecraft/server/BiomeBase.java b/src/main/java/net/minecraft/server/BiomeBase.java
index 260fd033c1017389a6f28447a6017b0ca15514d8..0854ac9ef586b378420d9899f3afd2755e6f9f33 100644
--- a/src/main/java/net/minecraft/server/BiomeBase.java
+++ b/src/main/java/net/minecraft/server/BiomeBase.java
@@ -209,9 +209,11 @@ public final class BiomeBase {
                     int l1 = j1 << 4;
 
                     try {
-                        structuremanager.a(SectionPosition.a(blockposition), structuregenerator).forEach((structurestart) -> {
-                            structurestart.a(regionlimitedworldaccess, structuremanager, chunkgenerator, seededrandom, new StructureBoundingBox(k1, l1, k1 + 15, l1 + 15), new ChunkCoordIntPair(i1, j1));
-                        });
+                        // Paper start - remove structure streams
+                        for (StructureStart<?> structureStart : structuremanager.getFeatureStarts(SectionPosition.a(blockposition), structuregenerator)) {
+                            structureStart.a(regionlimitedworldaccess, structuremanager, chunkgenerator, seededrandom, new StructureBoundingBox(k1, l1, k1 + 15, l1 + 15), new ChunkCoordIntPair(i1, j1));
+                        }
+                        // Paper end
                     } catch (Exception exception) {
                         CrashReport crashreport = CrashReport.a(exception, "Feature placement");
 
diff --git a/src/main/java/net/minecraft/server/ChunkGeneratorAbstract.java b/src/main/java/net/minecraft/server/ChunkGeneratorAbstract.java
index 4741d28aec73ffa1d5a9f60a4086eac3375c83b1..321ebe8891defb46f3ad3dfea37c9bb6e2025ad7 100644
--- a/src/main/java/net/minecraft/server/ChunkGeneratorAbstract.java
+++ b/src/main/java/net/minecraft/server/ChunkGeneratorAbstract.java
@@ -421,7 +421,7 @@ public final class ChunkGeneratorAbstract extends ChunkGenerator {
         while (iterator.hasNext()) {
             StructureGenerator<?> structuregenerator = (StructureGenerator) iterator.next();
 
-            structuremanager.a(SectionPosition.a(chunkcoordintpair, 0), structuregenerator).forEach((structurestart) -> {
+            for (StructureStart<?> structurestart : structuremanager.getFeatureStarts(SectionPosition.a(chunkcoordintpair, 0), structuregenerator)) { // Paper - remove structure streams
                 Iterator iterator1 = structurestart.d().iterator();
 
                 while (iterator1.hasNext()) {
@@ -453,7 +453,7 @@ public final class ChunkGeneratorAbstract extends ChunkGenerator {
                     }
                 }
 
-            });
+            } // Paper - remove structure streams
         }
 
         double[][][] adouble = new double[2][this.p + 1][this.o + 1];
diff --git a/src/main/java/net/minecraft/server/StructureManager.java b/src/main/java/net/minecraft/server/StructureManager.java
index c434427ce7bd206ed5d2efa2560e593b1186c666..f199368a6d78b0cd52f11ca2c8509d729b918852 100644
--- a/src/main/java/net/minecraft/server/StructureManager.java
+++ b/src/main/java/net/minecraft/server/StructureManager.java
@@ -1,12 +1,13 @@
 package net.minecraft.server;
 
 import com.mojang.datafixers.DataFixUtils;
+import it.unimi.dsi.fastutil.objects.ObjectArrayList; // Paper
 import java.util.stream.Stream;
 import javax.annotation.Nullable;
 
 public class StructureManager {
 
-    private final GeneratorAccess a;
+    private final GeneratorAccess a; public GeneratorAccess getLevel() { return a; } // Paper - OBFHELPER
     private final GeneratorSettings b;
 
     public StructureManager(GeneratorAccess generatoraccess, GeneratorSettings generatorsettings) {
@@ -32,6 +33,20 @@ public class StructureManager {
         });
     }
 
+    // Paper start - remove structure streams
+    public java.util.List<StructureStart<?>> getFeatureStarts(SectionPosition sectionPosition, StructureGenerator<?> structureGenerator) {
+        java.util.List<StructureStart<?>> list = new ObjectArrayList<>();
+        for (Long curLong: getLevel().getChunkAt(sectionPosition.a(), sectionPosition.c(), ChunkStatus.STRUCTURE_REFERENCES).b(structureGenerator)) {
+            SectionPosition sectionPosition1 = SectionPosition.a(new ChunkCoordIntPair(curLong), 0);
+            StructureStart<?> structurestart = a(sectionPosition1, structureGenerator, getLevel().getChunkAt(sectionPosition1.a(), sectionPosition1.c(), ChunkStatus.STRUCTURE_STARTS));
+            if (structurestart != null && structurestart.e()) {
+                list.add(structurestart);
+            }
+        }
+        return list;
+    }
+    // Paper end
+
     @Nullable
     public StructureStart<?> a(SectionPosition sectionposition, StructureGenerator<?> structuregenerator, IStructureAccess istructureaccess) {
         return istructureaccess.a(structuregenerator);
@@ -50,13 +65,21 @@ public class StructureManager {
     }
 
     public StructureStart<?> a(BlockPosition blockposition, boolean flag, StructureGenerator<?> structuregenerator) {
-        return (StructureStart) DataFixUtils.orElse(this.a(SectionPosition.a(blockposition), structuregenerator).filter((structurestart) -> {
-            return structurestart.c().b((BaseBlockPosition) blockposition);
-        }).filter((structurestart) -> {
-            return !flag || structurestart.d().stream().anyMatch((structurepiece) -> {
-                return structurepiece.g().b((BaseBlockPosition) blockposition);
-            });
-        }).findFirst(), StructureStart.a);
+        // Paper start - remove structure streams
+        for (StructureStart<?> structurestart : getFeatureStarts(SectionPosition.a(blockposition), structuregenerator)) {
+            if (structurestart.c().b(blockposition)) {
+                if (!flag) {
+                    return structurestart;
+                }
+                for (StructurePiece structurepiece : structurestart.d()) {
+                    if (structurepiece.g().b(blockposition)) {
+                        return structurestart;
+                    }
+                }
+            }
+        }
+        return StructureStart.a;
+        // Paper end
     }
 
     // Spigot start
