From 77c4b26e6ce4d4c35b0789c361a9dda69c5a0d06 Mon Sep 17 00:00:00 2001
From: Hamish Milne <hamishmilne83@gmail.com>
Date: Sat, 11 Apr 2020 22:25:57 +0100
Subject: [PATCH] Attempt to improve save/load during frame advance

---
 src/citra_qt/main.cpp   |  3 ++
 src/core/core.cpp       | 67 +++++++++++++++++++++--------------------
 src/core/perf_stats.cpp | 12 +++++---
 src/core/perf_stats.h   |  1 +
 4 files changed, 46 insertions(+), 37 deletions(-)

diff --git a/src/citra_qt/main.cpp b/src/citra_qt/main.cpp
index 0ef1e5bb19..bd1c95c52e 100644
--- a/src/citra_qt/main.cpp
+++ b/src/citra_qt/main.cpp
@@ -706,6 +706,7 @@ void GMainWindow::ConnectMenuEvents() {
         if (emulation_running) {
             ui.action_Enable_Frame_Advancing->setChecked(true);
             ui.action_Advance_Frame->setEnabled(true);
+            Core::System::GetInstance().frame_limiter.SetFrameAdvancing(true);
             Core::System::GetInstance().frame_limiter.AdvanceFrame();
         }
     });
@@ -1640,6 +1641,7 @@ void GMainWindow::OnSaveState() {
     assert(action);
 
     Core::System::GetInstance().SendSignal(Core::System::Signal::Save, action->data().toUInt());
+    Core::System::GetInstance().frame_limiter.AdvanceFrame();
     newest_slot = action->data().toUInt();
 }
 
@@ -1648,6 +1650,7 @@ void GMainWindow::OnLoadState() {
     assert(action);
 
     Core::System::GetInstance().SendSignal(Core::System::Signal::Load, action->data().toUInt());
+    Core::System::GetInstance().frame_limiter.AdvanceFrame();
 }
 
 void GMainWindow::OnConfigure() {
diff --git a/src/core/core.cpp b/src/core/core.cpp
index 8768ba3e61..58f1ddefe9 100644
--- a/src/core/core.cpp
+++ b/src/core/core.cpp
@@ -89,6 +89,40 @@ System::ResultStatus System::RunLoop(bool tight_loop) {
         }
     }
 
+    Signal signal{Signal::None};
+    u32 param{};
+    {
+        std::lock_guard lock{signal_mutex};
+        if (current_signal != Signal::None) {
+            signal = current_signal;
+            param = signal_param;
+            current_signal = Signal::None;
+        }
+    }
+    switch (signal) {
+    case Signal::Reset:
+        Reset();
+        return ResultStatus::Success;
+    case Signal::Shutdown:
+        return ResultStatus::ShutdownRequested;
+    case Signal::Load: {
+        LOG_INFO(Core, "Begin load");
+        System::LoadState(param);
+        LOG_INFO(Core, "Load completed");
+        frame_limiter.WaitOnce();
+        return ResultStatus::Success;
+    }
+    case Signal::Save: {
+        LOG_INFO(Core, "Begin save");
+        System::SaveState(param);
+        LOG_INFO(Core, "Save completed");
+        frame_limiter.WaitOnce();
+        return ResultStatus::Success;
+    }
+    default:
+        break;
+    }
+
     // All cores should have executed the same amount of ticks. If this is not the case an event was
     // scheduled with a cycles_into_future smaller then the current downcount.
     // So we have to get those cores to the same global time first
@@ -163,39 +197,6 @@ System::ResultStatus System::RunLoop(bool tight_loop) {
     HW::Update();
     Reschedule();
 
-    Signal signal{Signal::None};
-    u32 param{};
-    {
-        std::lock_guard lock{signal_mutex};
-        if (current_signal != Signal::None) {
-            signal = current_signal;
-            param = signal_param;
-            current_signal = Signal::None;
-        }
-    }
-    switch (signal) {
-    case Signal::Reset:
-        Reset();
-        break;
-    case Signal::Shutdown:
-        return ResultStatus::ShutdownRequested;
-        break;
-    case Signal::Load: {
-        LOG_INFO(Core, "Begin load");
-        System::LoadState(param);
-        LOG_INFO(Core, "Load completed");
-        break;
-    }
-    case Signal::Save: {
-        LOG_INFO(Core, "Begin save");
-        System::SaveState(param);
-        LOG_INFO(Core, "Save completed");
-        break;
-    }
-    default:
-        break;
-    }
-
     return status;
 }
 
diff --git a/src/core/perf_stats.cpp b/src/core/perf_stats.cpp
index 94d6c17ca0..00ab24dbcd 100644
--- a/src/core/perf_stats.cpp
+++ b/src/core/perf_stats.cpp
@@ -117,6 +117,14 @@ double PerfStats::GetLastFrameTimeScale() {
     return duration_cast<DoubleSecs>(previous_frame_length).count() / FRAME_LENGTH;
 }
 
+void FrameLimiter::WaitOnce() {
+    if (frame_advancing_enabled) {
+        // Frame advancing is enabled: wait on event instead of doing framelimiting
+        frame_advance_event.Wait();
+        frame_advance_event.Reset();
+    }
+}
+
 void FrameLimiter::DoFrameLimiting(microseconds current_system_time_us) {
     if (frame_advancing_enabled) {
         // Frame advancing is enabled: wait on event instead of doing framelimiting
@@ -164,10 +172,6 @@ void FrameLimiter::SetFrameAdvancing(bool value) {
 }
 
 void FrameLimiter::AdvanceFrame() {
-    if (!frame_advancing_enabled) {
-        // Start frame advancing
-        frame_advancing_enabled = true;
-    }
     frame_advance_event.Set();
 }
 
diff --git a/src/core/perf_stats.h b/src/core/perf_stats.h
index 0ef5168faa..c7d22ef8ec 100644
--- a/src/core/perf_stats.h
+++ b/src/core/perf_stats.h
@@ -98,6 +98,7 @@ public:
      */
     void SetFrameAdvancing(bool value);
     void AdvanceFrame();
+    void WaitOnce();
 
 private:
     /// Emulated system time (in microseconds) at the last limiter invocation