From 182bb4c8ba030137b0e52650f63b8fe2ac051e07 Mon Sep 17 00:00:00 2001
From: DBotThePony <dbotthepony@yandex.ru>
Date: Fri, 18 Aug 2023 13:59:57 +0700
Subject: [PATCH] Make Codec2RecipeSerializer thread safe

---
 .../mc/otm/data/Codec2RecipeSerializer.kt         | 15 ++++++++++++---
 1 file changed, 12 insertions(+), 3 deletions(-)

diff --git a/src/main/kotlin/ru/dbotthepony/mc/otm/data/Codec2RecipeSerializer.kt b/src/main/kotlin/ru/dbotthepony/mc/otm/data/Codec2RecipeSerializer.kt
index bd43dd751..16e1830f7 100644
--- a/src/main/kotlin/ru/dbotthepony/mc/otm/data/Codec2RecipeSerializer.kt
+++ b/src/main/kotlin/ru/dbotthepony/mc/otm/data/Codec2RecipeSerializer.kt
@@ -18,16 +18,25 @@ import ru.dbotthepony.mc.otm.core.set
 import ru.dbotthepony.mc.otm.core.util.readBinaryJsonWithCodecIndirect
 import ru.dbotthepony.mc.otm.core.util.writeBinaryJsonWithCodec
 import kotlin.collections.ArrayDeque
+import kotlin.concurrent.getOrSet
 
 class Codec2RecipeSerializer<S : Recipe<*>> private constructor(
 	val empty: S?,
-	private val id: ArrayDeque<ResourceLocation>,
+
+	/**
+	 * [ThreadLocal] because optimization mods can (and probably should) parallelize recipe deserialization,
+	 * since RecipeSerializers are expected to be stateless. [Codec2RecipeSerializer], however, is stateful (threading PoV).
+	 * To make it stateless, [ThreadLocal] is used.
+	 */
+	private val idStack: ThreadLocal<ArrayDeque<ResourceLocation>>,
 	codec: (Codec2RecipeSerializer<S>.Context) -> Codec<S>,
 ) : Codec<S>, RecipeSerializer<S> {
-	constructor(empty: S?, codec: (Codec2RecipeSerializer<S>.Context) -> Codec<S>) : this(empty, ArrayDeque(), codec)
+	constructor(empty: S?, codec: (Codec2RecipeSerializer<S>.Context) -> Codec<S>) : this(empty, ThreadLocal(), codec)
 	constructor(supplier: (Codec2RecipeSerializer<S>.Context) -> Codec<S>) : this(null, supplier)
 
 	private val codec = codec.invoke(Context())
+	private val id: ArrayDeque<ResourceLocation>
+		get() = idStack.getOrSet { ArrayDeque() }
 
 	inner class Context() {
 		val id: ResourceLocation
@@ -65,7 +74,7 @@ class Codec2RecipeSerializer<S : Recipe<*>> private constructor(
 	}
 
 	fun <O : Recipe<*>> xmap(to: (S) -> O, from: (O) -> S): Codec2RecipeSerializer<O> {
-		return Codec2RecipeSerializer(empty?.let(to), id) { _ ->
+		return Codec2RecipeSerializer(empty?.let(to), idStack) { _ ->
 			codec.xmap(to, from)
 		}
 	}