From bc46089ab0ca7963ca3b5507969a3df0f2afca6c Mon Sep 17 00:00:00 2001
From: Sam Belliveau <sam.belliveau@gmail.com>
Date: Fri, 30 Dec 2022 14:56:08 -0500
Subject: [PATCH] PerformanceTracker: Use shared_mutex instead of mutex so
 multiple threads can read at the same time.

---
 .../Core/VideoCommon/PerformanceTracker.cpp   | 20 ++++++++++---------
 Source/Core/VideoCommon/PerformanceTracker.h  |  4 ++--
 2 files changed, 13 insertions(+), 11 deletions(-)

diff --git a/Source/Core/VideoCommon/PerformanceTracker.cpp b/Source/Core/VideoCommon/PerformanceTracker.cpp
index ffde157883..305fb35598 100644
--- a/Source/Core/VideoCommon/PerformanceTracker.cpp
+++ b/Source/Core/VideoCommon/PerformanceTracker.cpp
@@ -5,8 +5,10 @@
 
 #include <algorithm>
 #include <cmath>
-#include <implot.h>
 #include <iomanip>
+#include <mutex>
+
+#include <implot.h>
 
 #include "Common/CommonTypes.h"
 #include "Common/FileUtil.h"
@@ -36,7 +38,7 @@ PerformanceTracker::~PerformanceTracker()
 
 void PerformanceTracker::Reset()
 {
-  std::lock_guard lock{m_mutex};
+  std::unique_lock lock{m_mutex};
 
   QueueClear();
   m_last_time = Clock::now();
@@ -47,7 +49,7 @@ void PerformanceTracker::Reset()
 
 void PerformanceTracker::Count()
 {
-  std::lock_guard lock{m_mutex};
+  std::unique_lock lock{m_mutex};
 
   if (m_paused)
     return;
@@ -97,19 +99,19 @@ DT PerformanceTracker::GetSampleWindow() const
 
 double PerformanceTracker::GetHzAvg() const
 {
-  std::lock_guard lock{m_mutex};
+  std::shared_lock lock{m_mutex};
   return m_hz_avg;
 }
 
 DT PerformanceTracker::GetDtAvg() const
 {
-  std::lock_guard lock{m_mutex};
+  std::shared_lock lock{m_mutex};
   return m_dt_avg;
 }
 
 DT PerformanceTracker::GetDtStd() const
 {
-  std::lock_guard lock{m_mutex};
+  std::unique_lock lock{m_mutex};
 
   if (m_dt_std)
     return *m_dt_std;
@@ -130,7 +132,7 @@ DT PerformanceTracker::GetDtStd() const
 
 DT PerformanceTracker::GetLastRawDt() const
 {
-  std::lock_guard lock{m_mutex};
+  std::shared_lock lock{m_mutex};
 
   if (QueueEmpty())
     return DT::zero();
@@ -142,7 +144,7 @@ void PerformanceTracker::ImPlotPlotLines(const char* label) const
 {
   static std::array<float, MAX_DT_QUEUE_SIZE + 2> x, y;
 
-  std::lock_guard lock{m_mutex};
+  std::shared_lock lock{m_mutex};
 
   if (QueueEmpty())
     return;
@@ -238,7 +240,7 @@ void PerformanceTracker::LogRenderTimeToFile(DT val)
 
 void PerformanceTracker::SetPaused(bool paused)
 {
-  std::lock_guard lock{m_mutex};
+  std::unique_lock lock{m_mutex};
 
   m_paused = paused;
   if (m_paused)
diff --git a/Source/Core/VideoCommon/PerformanceTracker.h b/Source/Core/VideoCommon/PerformanceTracker.h
index e253f83352..4136664981 100644
--- a/Source/Core/VideoCommon/PerformanceTracker.h
+++ b/Source/Core/VideoCommon/PerformanceTracker.h
@@ -6,8 +6,8 @@
 #include <array>
 #include <chrono>
 #include <fstream>
-#include <mutex>
 #include <optional>
+#include <shared_mutex>
 
 #include "Common/CommonTypes.h"
 
@@ -100,5 +100,5 @@ private:  // Functions for managing dt queue
   mutable std::optional<DT> m_dt_std = std::nullopt;
 
   // Used to enable thread safety with the performance tracker
-  mutable std::mutex m_mutex;
+  mutable std::shared_mutex m_mutex;
 };