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.
---
 .../PreciseSleep/IPreciseSleepEvent.cs             | 38 ++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 src/Ryujinx.Common/PreciseSleep/IPreciseSleepEvent.cs

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

diff --git a/src/Ryujinx.Common/PreciseSleep/IPreciseSleepEvent.cs b/src/Ryujinx.Common/PreciseSleep/IPreciseSleepEvent.cs
new file mode 100644
index 00000000..26b5ab68
--- /dev/null
+++ b/src/Ryujinx.Common/PreciseSleep/IPreciseSleepEvent.cs
@@ -0,0 +1,38 @@
+using System;
+
+namespace Ryujinx.Common.PreciseSleep
+{
+    /// <summary>
+    /// An event which works similarly to an AutoResetEvent, but is backed by a
+    /// more precise timer that allows waits of less than a millisecond.
+    /// </summary>
+    public interface IPreciseSleepEvent : IDisposable
+    {
+        /// <summary>
+        /// Adjust a timepoint to better fit the host clock.
+        /// When no adjustment is made, the input timepoint will be returned.
+        /// </summary>
+        /// <param name="timePoint">Timepoint to adjust</param>
+        /// <param name="timeoutNs">Requested timeout in nanoseconds</param>
+        /// <returns>Adjusted timepoint</returns>
+        long AdjustTimePoint(long timePoint, long timeoutNs);
+
+        /// <summary>
+        /// Sleep until a timepoint, or a signal is received.
+        /// Given no signal, may wake considerably before, or slightly after the timeout.
+        /// </summary>
+        /// <param name="timePoint">Timepoint to sleep until</param>
+        /// <returns>True if signalled or waited, false if a wait could not be performed</returns>
+        bool SleepUntil(long timePoint);
+
+        /// <summary>
+        /// Sleep until a signal is received.
+        /// </summary>
+        void Sleep();
+
+        /// <summary>
+        /// Signal the event, waking any sleeping thread or the next attempted sleep.
+        /// </summary>
+        void Signal();
+    }
+}
-- 
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