From a643170426cfe57cdfffddde87229b5506c49de5 Mon Sep 17 00:00:00 2001
From: embeddedt <42941056+embeddedt@users.noreply.github.com>
Date: Sun, 18 May 2025 19:10:11 -0400
Subject: [PATCH] Implement more accurate fix for MC-183518

The game now sleeps precisely till the next tick, rather than still
waking up periodically

Co-authored-by: HaHaWTH <102713261+HaHaWTH@users.noreply.github.com>
---
 .../BlockableEventLoopMixin.java              | 23 ---------
 .../MinecraftServerMixin.java                 | 48 +++++++++++++++++++
 2 files changed, 48 insertions(+), 23 deletions(-)
 delete mode 100644 common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/fix_loop_spin_waiting/BlockableEventLoopMixin.java
 create mode 100644 common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/fix_loop_spin_waiting/MinecraftServerMixin.java

diff --git a/common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/fix_loop_spin_waiting/BlockableEventLoopMixin.java b/common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/fix_loop_spin_waiting/BlockableEventLoopMixin.java
deleted file mode 100644
index fba53257..00000000
--- a/common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/fix_loop_spin_waiting/BlockableEventLoopMixin.java
+++ /dev/null
@@ -1,23 +0,0 @@
-package org.embeddedt.modernfix.common.mixin.perf.fix_loop_spin_waiting;
-
-import net.minecraft.util.thread.BlockableEventLoop;
-import org.spongepowered.asm.mixin.Mixin;
-import org.spongepowered.asm.mixin.Overwrite;
-
-import java.util.concurrent.TimeUnit;
-import java.util.concurrent.locks.LockSupport;
-
-// This should fix https://bugs.mojang.com/browse/MC-183518
-@Mixin(value = BlockableEventLoop.class, priority = 500)
-public class BlockableEventLoopMixin {
-    private static final long MFIX$TICK_WAIT_TIME = TimeUnit.MILLISECONDS.toNanos(2);
-
-    /**
-     * @author embeddedt
-     * @reason yielding the thread is pretty pointless if we're about to park anyway
-     */
-    @Overwrite
-    protected void waitForTasks() {
-        LockSupport.parkNanos("waiting for tasks", MFIX$TICK_WAIT_TIME);
-    }
-}
diff --git a/common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/fix_loop_spin_waiting/MinecraftServerMixin.java b/common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/fix_loop_spin_waiting/MinecraftServerMixin.java
new file mode 100644
index 00000000..e7ae6924
--- /dev/null
+++ b/common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/fix_loop_spin_waiting/MinecraftServerMixin.java
@@ -0,0 +1,48 @@
+package org.embeddedt.modernfix.common.mixin.perf.fix_loop_spin_waiting;
+
+import com.llamalad7.mixinextras.injector.wrapoperation.Operation;
+import com.llamalad7.mixinextras.injector.wrapoperation.WrapOperation;
+import net.minecraft.Util;
+import net.minecraft.server.MinecraftServer;
+import net.minecraft.util.thread.BlockableEventLoop;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.Shadow;
+import org.spongepowered.asm.mixin.Unique;
+import org.spongepowered.asm.mixin.injection.At;
+
+import java.util.concurrent.locks.LockSupport;
+import java.util.function.BooleanSupplier;
+
+@Mixin(value = MinecraftServer.class, priority = 500)
+public abstract class MinecraftServerMixin extends BlockableEventLoop<Runnable> {
+    @Shadow private long nextTickTime;
+
+    protected MinecraftServerMixin(String name) {
+        super(name);
+    }
+
+    @Unique
+    private boolean mfix$isWaitingForNextTick = false;
+
+    @WrapOperation(
+            method = "waitUntilNextTick",
+            at = @At(value = "INVOKE", target = "Lnet/minecraft/server/MinecraftServer;managedBlock(Ljava/util/function/BooleanSupplier;)V")
+    )
+    private void managedBlock(MinecraftServer instance, BooleanSupplier isDone, Operation<Void> original) {
+        try {
+            this.mfix$isWaitingForNextTick = true;
+            original.call(instance, isDone);
+        } finally {
+            this.mfix$isWaitingForNextTick = false;
+        }
+    }
+
+    @Override
+    protected void waitForTasks() {
+        if (this.mfix$isWaitingForNextTick) {
+            LockSupport.parkNanos("waiting for tasks", (this.nextTickTime * 1000000L) - Util.getNanos());
+        } else {
+            super.waitForTasks();
+        }
+    }
+}