From cf0ee05da60a5e7aaf4ed852e557629aca0c05ee Mon Sep 17 00:00:00 2001
From: Xphalnos <164882787+Xphalnos@users.noreply.github.com>
Date: Fri, 25 Oct 2024 20:03:20 +0200
Subject: [PATCH] [MISC] Allow user to override process priority class

---
 src/xenia/base/system.h           |  2 ++
 src/xenia/base/system_android.cc  |  2 ++
 src/xenia/base/system_gnulinux.cc |  2 ++
 src/xenia/base/system_win.cc      | 16 ++++++++++++++++
 src/xenia/emulator.cc             | 13 +++++++++++++
 5 files changed, 35 insertions(+)

diff --git a/src/xenia/base/system.h b/src/xenia/base/system.h
index b77bdbc69..519d954e1 100644
--- a/src/xenia/base/system.h
+++ b/src/xenia/base/system.h
@@ -27,6 +27,8 @@ void ShutdownAndroidSystem();
 void LaunchWebBrowser(const std::string_view url);
 void LaunchFileExplorer(const std::filesystem::path& path);
 
+bool SetProcessPriorityClass(const uint32_t priority_class);
+
 enum class SimpleMessageBoxType {
   Help,
   Warning,
diff --git a/src/xenia/base/system_android.cc b/src/xenia/base/system_android.cc
index 25c14a7bc..262c9d419 100644
--- a/src/xenia/base/system_android.cc
+++ b/src/xenia/base/system_android.cc
@@ -294,4 +294,6 @@ void ShowSimpleMessageBox(SimpleMessageBoxType type, std::string_view message) {
   // Java VM for the calling thread is needed.
 }
 
+bool SetProcessPriorityClass(const uint32_t priority_class) { return true; }
+
 }  // namespace xe
diff --git a/src/xenia/base/system_gnulinux.cc b/src/xenia/base/system_gnulinux.cc
index 920c9ab9e..a5421241f 100644
--- a/src/xenia/base/system_gnulinux.cc
+++ b/src/xenia/base/system_gnulinux.cc
@@ -67,4 +67,6 @@ void ShowSimpleMessageBox(SimpleMessageBoxType type, std::string_view message) {
   }
 }
 
+bool SetProcessPriorityClass(const uint32_t priority_class) { return true; }
+
 }  // namespace xe
diff --git a/src/xenia/base/system_win.cc b/src/xenia/base/system_win.cc
index ae77ae1d4..cd0ae622d 100644
--- a/src/xenia/base/system_win.cc
+++ b/src/xenia/base/system_win.cc
@@ -7,6 +7,7 @@
  ******************************************************************************
  */
 
+#include <map>
 #include "xenia/base/platform_win.h"
 #include "xenia/base/string.h"
 #include "xenia/base/system.h"
@@ -48,4 +49,19 @@ void ShowSimpleMessageBox(SimpleMessageBoxType type,
               type_flags);
 }
 
+static std::map<const uint32_t, DWORD> xeniaToWindowsPriorityClassMapping = {
+    {0, NORMAL_PRIORITY_CLASS},
+    {1, ABOVE_NORMAL_PRIORITY_CLASS},
+    {2, HIGH_PRIORITY_CLASS},
+    {3, REALTIME_PRIORITY_CLASS}};
+
+bool SetProcessPriorityClass(const uint32_t priority_class) {
+  if (!xeniaToWindowsPriorityClassMapping.count(priority_class)) {
+    return false;
+  }
+
+  return SetPriorityClass(GetCurrentProcess(),
+                          xeniaToWindowsPriorityClassMapping[priority_class]);
+}
+
 }  // namespace xe
diff --git a/src/xenia/emulator.cc b/src/xenia/emulator.cc
index 952e28de1..8e00cb0ae 100644
--- a/src/xenia/emulator.cc
+++ b/src/xenia/emulator.cc
@@ -86,6 +86,12 @@ DECLARE_int32(user_language);
 
 DECLARE_bool(allow_plugins);
 
+DEFINE_int32(priority_class, 0,
+             "Forces Xenia to use different process priority than default one. "
+             "It might affect performance and cause unexpected bugs. Possible "
+             "values: 0 - Normal, 1 - Above normal, 2 - High",
+             "General");
+
 namespace xe {
 using namespace xe::literals;
 
@@ -125,6 +131,13 @@ Emulator::Emulator(const std::filesystem::path& command_line,
       paused_(false),
       restoring_(false),
       restore_fence_() {
+  if (cvars::priority_class != 0) {
+    if (SetProcessPriorityClass(cvars::priority_class)) {
+      XELOGI("Higher priority class request: Successful. New priority: {}",
+             cvars::priority_class);
+    }
+  }
+
 #if XE_PLATFORM_WIN32 == 1
   // Show a disclaimer that links to the quickstart
   // guide the first time they ever open the emulator