From 1be668e68a1937f2af239e2707ab914286018892 Mon Sep 17 00:00:00 2001
From: riperiperi <rhy3756547@hotmail.com>
Date: Thu, 30 Nov 2023 10:39:42 -0800
Subject: HLE: Add OS-specific precise sleep methods to reduce spinwaiting
 (#5948)

* feat: add nanosleep for linux and macos

* Add Windows 0.5ms sleep

- Imprecise waits for longer waits with clock alignment
- 1/4 the spin time on vsync timer

* Remove old experiment

* Fix event leak

* Tweaking for MacOS

* Linux tweaks, nanosleep vsync improvement

* Fix overbias

* Cleanup

* Fix realignment

* Add some docs and some cleanup

NanosleepPool needs more, Nanosleep has some benchmark code that needs removed.

* Rename "Microsleep" to "PreciseSleep"

Might have been confused with "microseconds", which no measurement is performed in.

* Remove nanosleep measurement

* Remove unused debug logging

* Nanosleep Pool Documentation

* More cleanup

* Whitespace

* Formatting

* Address Feedback

* Allow SleepUntilTimePoint to take EventWaitHandle

* Remove `_chrono` stopwatch in SurfaceFlinger

* Move spinwaiting logic to PreciseSleepHelper

Technically, these achieve different things, but having them here makes them easier to reuse or tune.
---
 src/Ryujinx.Common/PreciseSleep/SleepEvent.cs | 51 +++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 src/Ryujinx.Common/PreciseSleep/SleepEvent.cs

(limited to 'src/Ryujinx.Common/PreciseSleep/SleepEvent.cs')

diff --git a/src/Ryujinx.Common/PreciseSleep/SleepEvent.cs b/src/Ryujinx.Common/PreciseSleep/SleepEvent.cs
new file mode 100644
index 00000000..f0769d1e
--- /dev/null
+++ b/src/Ryujinx.Common/PreciseSleep/SleepEvent.cs
@@ -0,0 +1,51 @@
+using System;
+using System.Threading;
+
+namespace Ryujinx.Common.PreciseSleep
+{
+    /// <summary>
+    /// A cross-platform precise sleep event that has millisecond granularity.
+    /// </summary>
+    internal class SleepEvent : IPreciseSleepEvent
+    {
+        private readonly AutoResetEvent _waitEvent = new(false);
+
+        public long AdjustTimePoint(long timePoint, long timeoutNs)
+        {
+            // No adjustment
+            return timePoint;
+        }
+
+        public bool SleepUntil(long timePoint)
+        {
+            long now = PerformanceCounter.ElapsedTicks;
+            long ms = Math.Min((timePoint - now) / PerformanceCounter.TicksPerMillisecond, int.MaxValue);
+
+            if (ms > 0)
+            {
+                _waitEvent.WaitOne((int)ms);
+
+                return true;
+            }
+
+            return false;
+        }
+
+        public void Sleep()
+        {
+            _waitEvent.WaitOne();
+        }
+
+        public void Signal()
+        {
+            _waitEvent.Set();
+        }
+
+        public void Dispose()
+        {
+            GC.SuppressFinalize(this);
+
+            _waitEvent.Dispose();
+        }
+    }
+}
-- 
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