Fix MC-183518

Author: embeddedt

common/src/main/java/org/embeddedt/modernfix/common/mixin/perf/fix_loop_spin_waiting/BlockableEventLoopMixin.java

@@ -0,0 +1,32 @@
+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.injection.At;
+import org.spongepowered.asm.mixin.injection.ModifyArg;
+import org.spongepowered.asm.mixin.injection.Redirect;
+
+import java.util.concurrent.TimeUnit;
+
+// This should fix https://bugs.mojang.com/browse/MC-183518
+@Mixin(BlockableEventLoop.class)
+public class BlockableEventLoopMixin {
+    /**
+     * @author embeddedt
+     * @reason yielding the thread is pretty pointless if we're about to park anyway
+     */
+    @Redirect(method = "waitForTasks", at = @At(value = "INVOKE", target = "Ljava/lang/Thread;yield()V"), require = 0)
+    private void doNotYield() {}
+
+    private static final long MFIX$TICK_WAIT_TIME = TimeUnit.MILLISECONDS.toNanos(2);
+
+    /**
+     * @author embeddedt
+     * @reason park for more than 0.1ms at a time. Task submission will call unpark(), so the thread will become
+     * runnable again if a task is submitted.
+     */
+    @ModifyArg(method = "waitForTasks", at = @At(value = "INVOKE", target = "Ljava/util/concurrent/locks/LockSupport;parkNanos(Ljava/lang/Object;J)V"), index = 1, require = 0)
+    private long changeParkDuration(long originalDuration) {
+        return MFIX$TICK_WAIT_TIME;
+    }
+}