From c99404dfb0cfcad609f6cfed655ba4982f71f9ea Mon Sep 17 00:00:00 2001
From: ImplementsLegend <thsmpsns50@gmail.com>
Date: Wed, 25 Sep 2024 16:52:05 +0200
Subject: [PATCH] improved performance of WeightedListProcessor

---
 .../mod/vaultfaster/FastWeightedList.kt       | 51 +++++++++++++++++++
 .../mixin/MixinWeightedProcessor.java         | 28 ++++++++++
 src/main/resources/vaultfaster.mixins.json    |  1 +
 3 files changed, 80 insertions(+)
 create mode 100644 src/main/java/implementslegend/mod/vaultfaster/FastWeightedList.kt
 create mode 100644 src/main/java/implementslegend/mod/vaultfaster/mixin/MixinWeightedProcessor.java

diff --git a/src/main/java/implementslegend/mod/vaultfaster/FastWeightedList.kt b/src/main/java/implementslegend/mod/vaultfaster/FastWeightedList.kt
new file mode 100644
index 0000000..4b85555
--- /dev/null
+++ b/src/main/java/implementslegend/mod/vaultfaster/FastWeightedList.kt
@@ -0,0 +1,51 @@
+package implementslegend.mod.vaultfaster
+
+import iskallia.vault.core.random.RandomSource
+import iskallia.vault.util.data.WeightedList
+import java.util.random.RandomGenerator
+import kotlin.random.Random
+
+class FastWeightedList<T> private constructor(capacity:Int) {
+
+    var totalWeight:Float = 0f
+
+    var weights = FloatArray(capacity)
+    var values = ArrayList<T>(capacity)
+
+    val entries = weights.zip(values).filter { it.first!=0f }
+
+    constructor(w:iskallia.vault.core.util.WeightedList<T>):this(w.entries.size){
+        w.entries.sortedBy { it.value }.forEach {
+            mutableEntry ->
+            totalWeight+=mutableEntry.value.toFloat()
+            values+=mutableEntry.key
+            weights[values.size-1]=mutableEntry.value.toFloat()
+        }
+    }
+
+
+    constructor(w:WeightedList<T>):this(w.size){
+        w.sortedBy { it.weight }.forEachIndexed {
+                index, mutableEntry ->
+            totalWeight+=mutableEntry.weight.toFloat()
+            weights[index]=mutableEntry.weight.toFloat()
+            values[index]=mutableEntry.value
+        }
+    }
+
+
+    fun random(rng:RandomGenerator) = random(rng::nextFloat)
+    fun random(rng:RandomSource) = random(rng::nextFloat)
+    fun random(rng:Random) = random(rng::nextFloat)
+    fun random(rng:()->Float):T?{
+        if(totalWeight<=0f)return null
+        weights.foldIndexed(rng()*totalWeight){
+            idx,acc,weight->
+            if(acc<weight)return@random values[idx]
+            acc-weight
+        }
+        return values.last()
+    }
+
+
+}
\ No newline at end of file
diff --git a/src/main/java/implementslegend/mod/vaultfaster/mixin/MixinWeightedProcessor.java b/src/main/java/implementslegend/mod/vaultfaster/mixin/MixinWeightedProcessor.java
new file mode 100644
index 0000000..c5ca417
--- /dev/null
+++ b/src/main/java/implementslegend/mod/vaultfaster/mixin/MixinWeightedProcessor.java
@@ -0,0 +1,28 @@
+package implementslegend.mod.vaultfaster.mixin;
+
+import implementslegend.mod.vaultfaster.FastWeightedList;
+import iskallia.vault.core.random.RandomSource;
+import iskallia.vault.core.util.WeightedList;
+import iskallia.vault.core.world.data.tile.PartialTile;
+import iskallia.vault.core.world.processor.tile.TileProcessor;
+import iskallia.vault.core.world.processor.tile.WeightedTileProcessor;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.Redirect;
+
+import java.util.Optional;
+
+@Mixin(WeightedTileProcessor.class)
+public class MixinWeightedProcessor {
+    private FastWeightedList<PartialTile> cached;
+
+    @Redirect(method = "process(Liskallia/vault/core/world/data/tile/PartialTile;Liskallia/vault/core/world/processor/ProcessorContext;)Liskallia/vault/core/world/data/tile/PartialTile;",at= @At(value = "INVOKE", target = "Liskallia/vault/core/util/WeightedList;getRandom(Liskallia/vault/core/random/RandomSource;)Ljava/util/Optional;"),remap = false)
+    private Optional<PartialTile> fastRandom(WeightedList<PartialTile> instance, RandomSource random){
+        var list = cached;
+        if(list==null){
+            list=new FastWeightedList<>(instance);
+            cached=list;
+        }
+        return Optional.ofNullable(list.random(random));
+    }
+}
diff --git a/src/main/resources/vaultfaster.mixins.json b/src/main/resources/vaultfaster.mixins.json
index 7796453..6dc7002 100644
--- a/src/main/resources/vaultfaster.mixins.json
+++ b/src/main/resources/vaultfaster.mixins.json
@@ -31,6 +31,7 @@
         "MixinTemplate",
         "MixinTemplateProcessorModifier",
         "MixinVaultLayout",
+        "MixinWeightedProcessor",
         "NoBiomeDecorations",
         "OctahedralGroupFix",
         "PartialBlockIDAccessor",