Fix random crash on viewport change, potential crash even if the viewport size is not changed.

Author: genail

CHANGELOG.md

@@ -0,0 +1,7 @@
+# Changelog
+
+## 1.0.2
+
+### Fixes
+
+- Random crash on viewport change, potential crash even if the viewport size is not changed.

Source/BetaHubBugReporter/Private/BH_DoubleAsyncBuffer.h

@@ -0,0 +1,62 @@
+#include "HAL/CriticalSection.h"
+#include "Misc/ScopeLock.h"
+#include "Memory.h"
+
+template <typename T>
+class BH_DoubleAsyncBuffer
+{
+    T* CurrentBuffer;
+    T* BackBuffer;
+    int32 CurrentSize;
+    int32 BackBufferSize;
+
+    FCriticalSection CriticalSection;
+
+public:
+    BH_DoubleAsyncBuffer()
+        : CurrentSize(0), BackBufferSize(0)
+    {
+        CurrentBuffer = new T[0];
+        BackBuffer = new T[0];
+    }
+
+    ~BH_DoubleAsyncBuffer()
+    {
+        delete[] CurrentBuffer;
+        delete[] BackBuffer;
+    }
+
+    void MemCopyFrom(const T* Data, int32 Size)
+    {
+        FScopeLock Lock(&CriticalSection);
+        if (Size > BackBufferSize)
+        {
+            delete[] BackBuffer;
+            BackBufferSize = Size;
+            BackBuffer = new T[BackBufferSize];
+        }
+        FMemory::Memcpy(BackBuffer, Data, Size);
+    }
+
+    void SwapBuffers()
+    {
+        FScopeLock Lock(&CriticalSection);
+        T* TempBuffer = CurrentBuffer;
+        CurrentBuffer = BackBuffer;
+        BackBuffer = TempBuffer;
+
+        int32 TempSize = CurrentSize;
+        CurrentSize = BackBufferSize;
+        BackBufferSize = TempSize;
+    }
+
+    const T* GetCurrentBuffer() const
+    {
+        return CurrentBuffer;
+    }
+
+    int32 GetCurrentSize() const
+    {
+        return CurrentSize;
+    }
+};

Source/BetaHubBugReporter/Private/BH_GameRecorder.cpp

@@ -20,7 +20,7 @@ bool ConvertRAWSurfaceDataToFLinearColor(EPixelFormat Format, uint32 Width, uint
 #endif
 
 UBH_GameRecorder::UBH_GameRecorder(const FObjectInitializer& ObjectInitializer)
-    : Super(ObjectInitializer), bIsRecording(false), bCopyTextureStarted(false), StagingTexture(nullptr), RawDataWidth(0), RawDataHeight(0)
+    : Super(ObjectInitializer), bIsRecording(false), bCopyTextureStarted(false), StagingTexture(nullptr), BackTextureWidth(0), BackTextureHeight(0)
 {
     FrameBuffer = ObjectInitializer.CreateDefaultSubobject<UBH_FrameBuffer>(this, TEXT("FrameBuffer"));
 }
@@ -162,6 +162,17 @@ void UBH_GameRecorder::Tick(float DeltaTime)
     {
         AsyncTask(ENamedThreads::AnyBackgroundThreadNormalTask, [this]()
         {
+            FScopeLock Lock(&AsyncTextureProcessingLock);
+            
+            BackTextureLock.Lock();
+            TextureBuffer.SwapBuffers(); // swap back with current
+
+            const uint8 *RawData = reinterpret_cast<const uint8*>(TextureBuffer.GetCurrentBuffer());
+            int32 RawDataWidth = BackTextureWidth;
+            int32 RawDataHeight = BackTextureHeight;
+
+            BackTextureLock.Unlock();
+            
             // Make sure that PendingPixels is of the correct size
             int32 NumPixels = RawDataWidth * RawDataHeight;
 
@@ -175,7 +186,8 @@ void UBH_GameRecorder::Tick(float DeltaTime)
 
 
             // Convert raw surface data to linear color
-            ConvertRAWSurfaceDataToFLinearColor(StagingTextureFormat, RawDataWidth, RawDataHeight, reinterpret_cast<uint8*>(RawData), Pitch, PendingLinearPixels.GetData(), FReadSurfaceDataFlags({}));
+            ConvertRAWSurfaceDataToFLinearColor(StagingTextureFormat, RawDataWidth, RawDataHeight, const_cast<uint8*>(RawData),
+                Pitch, PendingLinearPixels.GetData(), FReadSurfaceDataFlags({}));
 
             // Convert linear color to FColor
             for (int32 i = 0; i < NumPixels; ++i)
@@ -323,7 +335,22 @@ void UBH_GameRecorder::ReadPixels()
             FRHICopyTextureInfo CopyInfo;
             RHICmdList.CopyTexture(GEngine->GameViewport->Viewport->GetRenderTargetTexture(), StagingTexture, CopyInfo);
 
-            RHICmdList.MapStagingSurface(StagingTexture, this->RawData, this->RawDataWidth, this->RawDataHeight);
+            void* RawDataTemp = nullptr;
+            int32 RawDataWidthTemp = 0;
+            int32 RawDataHeightTemp = 0;
+
+            RHICmdList.MapStagingSurface(StagingTexture, RawDataTemp, RawDataWidthTemp, RawDataHeightTemp);
+
+            // copy the memory, because RawDataTemp is temporary
+            BackTextureLock.Lock();
+
+            TextureBuffer.MemCopyFrom(
+                reinterpret_cast<uint8*>(RawDataTemp),
+                RawDataWidthTemp * RawDataHeightTemp * GPixelFormats[StagingTextureFormat].BlockBytes);
+            BackTextureWidth = RawDataWidthTemp;
+            BackTextureHeight = RawDataHeightTemp;
+
+            BackTextureLock.Unlock();
 
             RHICmdList.UnmapStagingSurface(StagingTexture);
         }

Source/BetaHubBugReporter/Private/BH_GameRecorder.h

@@ -1,11 +1,13 @@
 #pragma once
 
 #include "CoreMinimal.h"
+#include "Tickable.h"
+#include "HAL/CriticalSection.h"
 #include "BH_VideoEncoder.h"
 #include "BH_FrameBuffer.h"
-#include "Tickable.h"
 #include "UObject/NoExportTypes.h"
 #include "BH_SceneCaptureActor.h"
+#include "BH_DoubleAsyncBuffer.h"
 #include "BH_GameRecorder.generated.h"
 
 UCLASS()
@@ -64,9 +66,11 @@ class BETAHUBBUGREPORTER_API UBH_GameRecorder : public UObject, public FTickable
     int32 FrameHeight;
     FDateTime LastCaptureTime;
 
-    void *RawData;
-    int32 RawDataWidth;
-    int32 RawDataHeight;
+    BH_DoubleAsyncBuffer<uint8> TextureBuffer;
+    int32 BackTextureWidth;
+    int32 BackTextureHeight;
+    FCriticalSection BackTextureLock;
+    FCriticalSection AsyncTextureProcessingLock;
 
     void CaptureFrame();
     void CaptureRenderTargetFrame();