Refactor framerate limiter to reduce CPU consumption (#4385)

* Frame limiter refactor: queue-only ApplyFrameRateLimit, centralized pacing in ApplyQueuedFrameRateLimit

TL;DR: Main menu runs with arbitrary FPS limit now

- EnsureFrameRateLimitApplied no longer calls ApplyFrameRateLimit() from Present path
  to avoid skewed pacing; now only queues the target rate for the timer hook.
- ApplyFrameRateLimit simplified to just queue the requested rate.
- ApplyQueuedFrameRateLimit is now the single enforcement point:
  uses high-precision timing, adaptive sleep/yield calibration, and minimal spin
  to achieve stable pacing without wasting CPU.
- Added detailed comments clarifying responsibilities and caveats
  (e.g. Main Menu not using timer hook).

* refactor(core): implement high-precision FPS limiter

Replace scattered frame rate limiting logic with centralized `FPSLimiter` class.

**Key improvements:**
- High-precision timing using `RDTSC`, `QueryPerformanceFrequency`, and waitable timers
- Unified FPS limit handling from server, client scripts, user settings, and VSync
- Dynamic CEF browser frame rate synchronization
- Consistent frame pacing through `CModManager` pulse integration

**Changes:**
- Add `FPSLimiter` class with centralized frame limiting logic
- Integrate limiter into `CCore`, replacing old methods and variables
- Refactor `CCommands` to handle `fps_limit` and `vsync` cvars
- Update all APIs, Lua functions, and network packets to use `FPSLimiterInterface`

* Remove bug introduced by validating and loading flag in LoadDefaults

* Use `std::numeric_limits<uint32_t>::max()`

* `const noexcept` on `GetEnforcer` and `GetFPSTarget`

* No lambda for `CPacketHandler` and update referenced code

* `std::unique_ptr` instead of raw pointer

* No MTA versioning in comments for new files

* No SString, updated std:: members, logging removed, EnumToString, static_cast, and more.
- Cleanup CClientVariables::ValidateValues
- Removed // Easter egg! comment

* Reverted side-refactors and issued #4427

* CClientGame cleanup (Check #4428) and formatting

Given that I needed to touch I applied formatting

* Use stringstream for cleanliness

* More std:: members

* Use stringstream and reinterpret_cast function ptr typedef

* Tweaks

* Add V-Sync checkbox to settings

* Refactored the refactor to match guidelines and one of the last cleanups of code

* Wait for network module before updating webcore fps

---------

Co-authored-by: Marek Kulik <noreply@bug32.com>
Co-authored-by: Dutchman101 <12105539+Dutchman101@users.noreply.github.com>

Author: 3 people

Client/cefweb/CWebCore.cpp

@@ -479,6 +479,15 @@ void CWebCore::OnPostScreenshot()
     }
 }
 
+void CWebCore::OnFPSLimitChange(std::uint16_t fps)
+{
+    dassert(g_pCore->GetNetwork() != nullptr);            // Ensure network module is loaded
+    for (auto& webView : m_WebViews)
+    {
+        webView->GetCefBrowser()->GetHost()->SetWindowlessFrameRate(fps);
+    }
+}
+
 void CWebCore::ProcessInputMessage(UINT uMsg, WPARAM wParam, LPARAM lParam)
 {
     if (!m_pFocusedWebView ||

Client/cefweb/CWebCore.h

@@ -96,6 +96,8 @@ class CWebCore : public CWebCoreInterface
     void OnPreScreenshot();
     void OnPostScreenshot();
 
+    void OnFPSLimitChange(std::uint16_t fps) override;
+
     bool SetGlobalAudioVolume(float fVolume);
 
     bool        UpdateListsFromMaster();

Client/cefweb/CWebView.cpp

@@ -54,7 +54,7 @@ void CWebView::Initialise()
 {
     // Initialise the web session (which holds the actual settings) in in-memory mode
     CefBrowserSettings browserSettings;
-    browserSettings.windowless_frame_rate = g_pCore->GetFrameRateLimit();
+    browserSettings.windowless_frame_rate = g_pCore->GetFPSLimiter()->GetFPSTarget();
     browserSettings.javascript_access_clipboard = cef_state_t::STATE_DISABLED;
     browserSettings.javascript_dom_paste = cef_state_t::STATE_DISABLED;
     browserSettings.webgl = cef_state_t::STATE_ENABLED;

Client/core/CClientVariables.cpp

@@ -234,7 +234,15 @@ void CClientVariables::ValidateValues()
 
     ClampValue("console_pos", CVector2D(0, 0), CVector2D(uiViewportWidth - 32, uiViewportHeight - 32));
     ClampValue("console_size", CVector2D(50, 50), CVector2D(uiViewportWidth - 32, uiViewportHeight - 32));
-    ClampValue("fps_limit", 0, std::numeric_limits<short>::max());
+
+    // CVars need a better API for this (Issue #4427)
+    int temp;
+    CVARS_GET("fps_limit", temp);
+    std::uint16_t fps = static_cast<std::uint16_t>(temp);
+    FPSLimits::IsValidAndSetValid(fps, fps);
+    CVARS_SET("fps_limit", fps);
+
+
     ClampValue("chat_font", 0, 3);
     ClampValue("chat_lines", 3, 62);
     ClampValue("chat_color", CColor(0, 0, 0, 0), CColor(255, 255, 255, 255));
@@ -261,9 +269,10 @@ void CClientVariables::ValidateValues()
 
 void CClientVariables::LoadDefaults()
 {
-    #define DEFAULT(__x,__y)    if(!Exists(__x)) \
-                                Set(__x,__y)
-    #define _S(__x)             std::string(__x)
+#define DEFAULT(__x, __y) \
+    if (!Exists(__x)) \
+    Set(__x, __y)
+#define _S(__x) std::string(__x)
 
     if (!Exists("nick"))
     {
@@ -279,6 +288,7 @@ void CClientVariables::LoadDefaults()
     DEFAULT("console_size", CVector2D(200, 200));                        // console size
     DEFAULT("serverbrowser_size", CVector2D(720.0f, 495.0f));            // serverbrowser size
     DEFAULT("fps_limit", 100);                                           // frame limiter
+    DEFAULT("vsync", true);                                              // vsync
     DEFAULT("chat_font", 2);                                             // chatbox font type
     DEFAULT("chat_lines", 10);                                           // chatbox lines
     DEFAULT("chat_color", CColor(0, 0, 0, 0));                           // chatbox background color
@@ -379,4 +389,8 @@ void CClientVariables::LoadDefaults()
 #if 0
     DEFAULT ( "streaming_memory",           50 );                           // Streaming memory
 #endif
+
+#undef DEFAULT
+#undef _S
+
 }

Client/core/CCommands.cpp

@@ -85,7 +85,7 @@ bool CCommands::Execute(const char* szCommand, const char* szParametersIn, bool
 {
     // Copy szParametersIn so the contents can be changed
     char* szParameters = NULL;
-    char empyParameters[1] = { 0 };
+    char  empyParameters[1] = {0};
     if (szParametersIn)
     {
         size_t sizeParameters = strlen(szParametersIn) + 1;
@@ -172,10 +172,19 @@ bool CCommands::Execute(const char* szCommand, const char* szParametersIn, bool
                 CVARS_SET(key, val);
 
                 // HACK: recalculate frame rate limit on cvar change
-                if (key == "fps_limit" && m_FpsLimitTimer.Get() >= 500 && CCore::GetSingleton().IsConnected())
+                if (key == "fps_limit")
                 {
-                    CCore::GetSingleton().RecalculateFrameRateLimit(-1, true);
-                    m_FpsLimitTimer.Reset();
+                    int fpsVal = 0;
+                    CVARS_GET("fps_limit", fpsVal);
+                    CCore::GetSingleton().GetFPSLimiter()->SetUserDefinedFPS(fpsVal);
+                }
+
+                // HACK: Foul dirty hack to force vsync (Rework on #4427)
+                if (key == "vsync")
+                {
+                    bool vSync;
+                    CVARS_GET("vsync", vSync);
+                    CCore::GetSingleton().GetFPSLimiter()->SetDisplayVSync(vSync);
                 }
             }
             else

Client/core/CCommands.h

@@ -44,7 +44,5 @@ class CCommands : public CCommandsInterface, public CSingleton<CCommands>
     void ExecuteHandler(PFNCOMMAND pfnHandler, const char* szParameters);
 
     std::list<COMMANDENTRY*> m_CommandList;
-    CElapsedTime             m_FpsLimitTimer;
-
     pfnExecuteCommandHandler m_pfnExecuteHandler;
 };

Client/core/CCore.cpp

@@ -56,7 +56,7 @@ static HMODULE WINAPI SkipDirectPlay_LoadLibraryA(LPCSTR fileName)
     if (!StrCmpIA("enbseries\\enbhelper.dll", fileName))
     {
         std::error_code ec;
-        
+
         // Try to load enbhelper.dll from our custom launch directory first.
         const fs::path inLaunchDir = fs::path{FromUTF8(GetLaunchPath())} / "enbseries" / "enbhelper.dll";
 
@@ -146,18 +146,16 @@ CCore::CCore()
     // Setup our hooks.
     ApplyHooks();
 
-    // No initial fps limit
-    m_bDoneFrameRateLimit = false;
-    m_uiFrameRateLimit = 0;
-    m_uiServerFrameRateLimit = 0;
     m_iUnminimizeFrameCounter = 0;
     m_bDidRecreateRenderTargets = false;
     m_fMinStreamingMemory = 0;
     m_fMaxStreamingMemory = 0;
     m_bGettingIdleCallsFromMultiplayer = false;
     m_bWindowsTimerEnabled = false;
     m_timeDiscordAppLastUpdate = 0;
-    m_CurrentRefreshRate = 60;
+
+    // Initialize FPS limiter
+    m_pFPSLimiter = std::make_unique<FPSLimiter::FPSLimiter>();
 
     // Create tray icon
     m_pTrayIcon = new CTrayIcon();
@@ -180,6 +178,8 @@ CCore::~CCore()
     // Destroy tray icon
     delete m_pTrayIcon;
 
+    m_pFPSLimiter.reset();
+
     // This will set the GTA volume to the GTA volume value in the settings,
     // and is not affected by the master volume setting.
     m_pLocalGUI->GetMainMenu()->GetSettingsWindow()->ResetGTAVolume();
@@ -1347,7 +1347,7 @@ void CCore::OnModUnload()
     m_pKeyBinds->RemoveAllControlFunctions();
 
     // Reset client script frame rate limit
-    m_uiClientScriptFrameRateLimit = 0;
+    GetFPSLimiter()->SetClientEnforcedFPS(FPSLimits::FPS_UNLIMITED);
 
     // Clear web whitelist
     if (m_pWebCore)
@@ -1772,8 +1772,8 @@ void CCore::OnPostColorFilterRender()
 {
     if (!CGraphics::GetSingleton().HasLine3DPostFXQueueItems() && !CGraphics::GetSingleton().HasPrimitive3DPostFXQueueItems())
         return;
-    
-    CGraphics::GetSingleton().EnteringMTARenderZone();      
+
+    CGraphics::GetSingleton().EnteringMTARenderZone();
 
     CGraphics::GetSingleton().DrawPrimitive3DPostFXQueue();
     CGraphics::GetSingleton().DrawLine3DPostFXQueue();
@@ -1831,141 +1831,14 @@ void CCore::ApplyCoreInitSettings()
 //
 void CCore::OnGameTimerUpdate()
 {
-    ApplyQueuedFrameRateLimit();
+    // NOTE: (pxd) We are handling the frame limiting updates
+    // earlier in the callpath (CModManager::DoPulsePreFrame, CModManager::DoPulsePostFrame)
 }
 
-//
-// Recalculate FPS limit to use
-//
-// Uses client rate from config
-// Uses client rate from script
-// Uses server rate from argument, or last time if not supplied
-//
-void CCore::RecalculateFrameRateLimit(uint uiServerFrameRateLimit, bool bLogToConsole)
+void CCore::OnFPSLimitChange(std::uint16_t fps)
 {
-    // Save rate from server if valid
-    if (uiServerFrameRateLimit != -1)
-        m_uiServerFrameRateLimit = uiServerFrameRateLimit;
-
-    // Start with value set by the server
-    m_uiFrameRateLimit = m_uiServerFrameRateLimit;
-
-    // Apply client config setting
-    uint uiClientConfigRate;
-    g_pCore->GetCVars()->Get("fps_limit", uiClientConfigRate);
-    if (uiClientConfigRate > 0)
-        uiClientConfigRate = std::max(45U, uiClientConfigRate);
-    // Lowest wins (Although zero is highest)
-    if ((m_uiFrameRateLimit == 0 || uiClientConfigRate < m_uiFrameRateLimit) && uiClientConfigRate > 0)
-        m_uiFrameRateLimit = uiClientConfigRate;
-
-    // Apply client script setting
-    uint uiClientScriptRate = m_uiClientScriptFrameRateLimit;
-    // Lowest wins (Although zero is highest)
-    if ((m_uiFrameRateLimit == 0 || uiClientScriptRate < m_uiFrameRateLimit) && uiClientScriptRate > 0)
-        m_uiFrameRateLimit = uiClientScriptRate;
-
-    if (!IsConnected())
-        m_uiFrameRateLimit = m_CurrentRefreshRate;
-
-    // Removes Limiter from Frame Graph if limit is zero and skips frame limit
-    if (m_uiFrameRateLimit == 0)
-    {
-        m_bQueuedFrameRateValid = false;
-        GetGraphStats()->RemoveTimingPoint("Limiter");
-    }
-
-    // Print new limits to the console
-    if (bLogToConsole)
-    {
-        SString strStatus("Server FPS limit: %d", m_uiServerFrameRateLimit);
-        if (m_uiFrameRateLimit != m_uiServerFrameRateLimit)
-            strStatus += SString(" (Using %d)", m_uiFrameRateLimit);
-        CCore::GetSingleton().GetConsole()->Print(strStatus);
-    }
-}
-
-//
-// Change client rate as set by script
-//
-void CCore::SetClientScriptFrameRateLimit(uint uiClientScriptFrameRateLimit)
-{
-    m_uiClientScriptFrameRateLimit = uiClientScriptFrameRateLimit;
-    RecalculateFrameRateLimit(-1, false);
-}
-
-void CCore::SetCurrentRefreshRate(uint value)
-{
-    m_CurrentRefreshRate = value;
-    RecalculateFrameRateLimit(-1, false);
-}
-
-//
-// Make sure the frame rate limit has been applied since the last call
-//
-void CCore::EnsureFrameRateLimitApplied()
-{
-    if (!m_bDoneFrameRateLimit)
-    {
-        ApplyFrameRateLimit();
-    }
-    m_bDoneFrameRateLimit = false;
-}
-
-//
-// Do FPS limiting
-//
-// This is called once a frame even if minimized
-//
-void CCore::ApplyFrameRateLimit(uint uiOverrideRate)
-{
-    TIMING_CHECKPOINT("-CallIdle1");
-    ms_TimingCheckpoints.EndTimingCheckpoints();
-
-    // Frame rate limit stuff starts here
-    m_bDoneFrameRateLimit = true;
-
-    uint uiUseRate = uiOverrideRate != -1 ? uiOverrideRate : m_uiFrameRateLimit;
-
-    if (uiUseRate > 0)
-    {
-        // Apply previous frame rate if is hasn't been done yet
-        ApplyQueuedFrameRateLimit();
-
-        // Limit is usually applied in OnGameTimerUpdate
-        m_uiQueuedFrameRate = uiUseRate;
-        m_bQueuedFrameRateValid = true;
-    }
-
-    DoReliablePulse();
-
-    TIMING_GRAPH("FrameEnd");
-    TIMING_GRAPH("");
-}
-
-//
-// Frame rate limit (wait) is done here.
-//
-void CCore::ApplyQueuedFrameRateLimit()
-{
-    if (m_bQueuedFrameRateValid)
-    {
-        m_bQueuedFrameRateValid = false;
-        // Calc required time in ms between frames
-        const double dTargetTimeToUse = 1000.0 / m_uiQueuedFrameRate;
-
-        while (true)
-        {
-            // See if we need to wait
-            double dSpare = dTargetTimeToUse - m_FrameRateTimer.Get();
-            if (dSpare <= 0.0)
-                break;
-            if (dSpare >= 10.0)
-                Sleep(1);
-        }
-        m_FrameRateTimer.Reset();
-        TIMING_GRAPH("Limiter");
-    }
+    if (m_pNet != nullptr)            // We have to wait for the network module to be loaded
+        GetWebCore()->OnFPSLimitChange(fps);
 }
 
 //
@@ -2020,7 +1893,7 @@ void CCore::OnDeviceRestore()
 void CCore::OnPreFxRender()
 {
     if (!CGraphics::GetSingleton().HasLine3DPreGUIQueueItems() && !CGraphics::GetSingleton().HasPrimitive3DPreGUIQueueItems())
-        return;    
+        return;
 
     CGraphics::GetSingleton().EnteringMTARenderZone();
 
@@ -2035,7 +1908,7 @@ void CCore::OnPreFxRender()
 //
 void CCore::OnPreHUDRender()
 {
-    CGraphics::GetSingleton().EnteringMTARenderZone();    
+    CGraphics::GetSingleton().EnteringMTARenderZone();
 
     // Maybe capture screen and other stuff
     CGraphics::GetSingleton().GetRenderItemManager()->DoPulse();
@@ -2396,7 +2269,8 @@ SString CCore::GetBlueCopyrightString()
 
 // Set streaming memory size override [See `engineStreamingSetMemorySize`]
 // Use `0` to turn it off, and thus restore the value to the `cvar` setting
-void CCore::SetCustomStreamingMemory(size_t sizeBytes) {
+void CCore::SetCustomStreamingMemory(size_t sizeBytes)
+{
     // NOTE: The override is applied to the game in `CClientGame::DoPulsePostFrame`
     // There's no specific reason we couldn't do it here, but we wont
     m_CustomStreamingMemoryLimitBytes = sizeBytes;