58 lines
2.8 KiB
Java
58 lines
2.8 KiB
Java
package dev.modzuozhi.mixin;
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import net.minecraft.world.entity.item.ItemEntity;
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import net.minecraft.world.level.block.Block;
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import org.objectweb.asm.Opcodes;
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import org.spongepowered.asm.mixin.Mixin;
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import org.spongepowered.asm.mixin.Unique;
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import org.spongepowered.asm.mixin.injection.At;
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import org.spongepowered.asm.mixin.injection.Redirect;
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import java.util.ArrayList;
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import java.util.List;
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/**
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* 让 NeoForge 的方块掉落捕获对多线程安全。
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* <p>
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* NeoForge 在 {@code Block.dropResources} 中通过<b>全局静态字段</b> {@code Block.capturedDrops}
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* 临时捕获本方块掉落的 {@code ItemEntity}（详见 {@code beginCapturingDrops}/{@code stopCapturingDrops}，
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* 注释明确要求「只在服务端线程调用」）。维度并行 / 细粒度并行下，多个线程并发执行随机 tick
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* （树叶凋零、方块燃烧等）都会进入 {@code dropResources}，并发读写该静态字段会互相覆盖：
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* 某个线程的 {@code stopCapturingDrops()} 会读到已被另一线程清空的 {@code null}，导致
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* {@code BlockDropsEvent.getDrops()} 为 null 而 NPE（日志中 {@code CommonHooks.handleBlockDrops}
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* 的崩溃即源于此），并连带产生 {@code ClassCastException}。
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* <p>
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* 这里把掉落捕获改为<b>线程本地</b>：每个线程维护独立的捕获列表，从根上消除跨线程污染。
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* 语义与原版一致（仅在捕获开始到结束之间拦截掉落），但并行安全。
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*/
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@Mixin(Block.class)
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public abstract class BlockDropCaptureMixin {
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/** 线程本地掉落捕获列表，替代原版全局静态 {@code Block.capturedDrops}。 */
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@Unique
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private static final ThreadLocal<List<ItemEntity>> modzuozhi_capturedDrops = new ThreadLocal<>();
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@Redirect(method = "dropResources",
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at = @At(value = "INVOKE",
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target = "Lnet/minecraft/world/level/block/Block;beginCapturingDrops()V"))
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private static void modzuozhi_beginCapture() {
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modzuozhi_capturedDrops.set(new ArrayList<>());
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}
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@Redirect(method = "dropResources",
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at = @At(value = "INVOKE",
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target = "Lnet/minecraft/world/level/block/Block;stopCapturingDrops()Ljava/util/List;"))
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private static List<ItemEntity> modzuozhi_stopCapture() {
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List<ItemEntity> drops = modzuozhi_capturedDrops.get();
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modzuozhi_capturedDrops.remove();
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return drops;
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}
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@Redirect(method = "popResource(Lnet/minecraft/world/level/Level;Ljava/util/function/Supplier;Lnet/minecraft/world/item/ItemStack;)V",
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at = @At(value = "FIELD",
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target = "Lnet/minecraft/world/level/block/Block;capturedDrops:Ljava/util/List;",
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opcode = Opcodes.GETSTATIC))
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private static List<ItemEntity> modzuozhi_capturedGet() {
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return modzuozhi_capturedDrops.get();
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}
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}
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