[gfx][Skia] Hold mutex while accessing shared SkImage data.

3 files changed, 54 insertions, 17 deletions

diff --git a/gfx/2d/DrawTargetSkia.cpp b/gfx/2d/DrawTargetSkia.cpp
index 9eaac5674..7e71e54cc 100644
--- a/gfx/2d/DrawTargetSkia.cpp
+++ b/gfx/2d/DrawTargetSkia.cpp
@@ -212,7 +212,7 @@ VerifyRGBXCorners(uint8_t* aData, const IntSize &aSize, const int32_t aStride, S
 #endif
 
 static sk_sp<SkImage>
-GetSkImageForSurface(SourceSurface* aSurface)
+GetSkImageForSurface(SourceSurface* aSurface, Maybe<MutexAutoLock>* aLock)
 {
   if (!aSurface) {
     gfxDebug() << "Creating null Skia image from null SourceSurface";
@@ -220,7 +220,7 @@ GetSkImageForSurface(SourceSurface* aSurface)
   }
 
   if (aSurface->GetType() == SurfaceType::SKIA) {
-    return static_cast<SourceSurfaceSkia*>(aSurface)->GetImage();
+    return static_cast<SourceSurfaceSkia*>(aSurface)->GetImage(aLock);
   }
 
   DataSourceSurface* surf = aSurface->GetDataSurface().take();
@@ -390,9 +390,9 @@ ExtractAlphaBitmap(sk_sp<SkImage> aImage, SkBitmap* aResultBitmap)
 }
 
 static sk_sp<SkImage>
-ExtractAlphaForSurface(SourceSurface* aSurface)
+ExtractAlphaForSurface(SourceSurface* aSurface, Maybe<MutexAutoLock>& aLock)
 {
-  sk_sp<SkImage> image = GetSkImageForSurface(aSurface);
+  sk_sp<SkImage> image = GetSkImageForSurface(aSurface, &aLock);
   if (!image) {
     return nullptr;
   }
@@ -411,7 +411,11 @@ ExtractAlphaForSurface(SourceSurface* aSurface)
 }
 
 static void
-SetPaintPattern(SkPaint& aPaint, const Pattern& aPattern, Float aAlpha = 1.0, Point aOffset = Point(0, 0))
+SetPaintPattern(SkPaint& aPaint,
+                const Pattern& aPattern,
+                Maybe<MutexAutoLock>& aLock,
+                Float aAlpha = 1.0,
+                Point aOffset = Point(0, 0))
 {
   switch (aPattern.GetType()) {
     case PatternType::COLOR: {
@@ -473,7 +477,7 @@ SetPaintPattern(SkPaint& aPaint, const Pattern& aPattern, Float aAlpha = 1.0, Po
     }
     case PatternType::SURFACE: {
       const SurfacePattern& pat = static_cast<const SurfacePattern&>(aPattern);
-      sk_sp<SkImage> image = GetSkImageForSurface(pat.mSurface);
+      sk_sp<SkImage> image = GetSkImageForSurface(pat.mSurface, &aLock);
       if (!image) {
         aPaint.setColor(SK_ColorTRANSPARENT);
         break;
@@ -525,7 +529,7 @@ struct AutoPaintSetup {
     : mNeedsRestore(false), mAlpha(1.0)
   {
     Init(aCanvas, aOptions, aMaskBounds, false);
-    SetPaintPattern(mPaint, aPattern, mAlpha, aOffset);
+    SetPaintPattern(mPaint, aPattern, mLock, mAlpha, aOffset);
   }
 
   AutoPaintSetup(SkCanvas *aCanvas, const DrawOptions& aOptions, const Rect* aMaskBounds = nullptr, bool aForceGroup = false)
@@ -579,6 +583,7 @@ struct AutoPaintSetup {
   SkPaint mPaint;
   bool mNeedsRestore;
   SkCanvas* mCanvas;
+  Maybe<MutexAutoLock> mLock;
   Float mAlpha;
 };
 
@@ -601,7 +606,8 @@ DrawTargetSkia::DrawSurface(SourceSurface *aSurface,
 
   MarkChanged();
 
-  sk_sp<SkImage> image = GetSkImageForSurface(aSurface);
+  Maybe<MutexAutoLock> lock;
+  sk_sp<SkImage> image = GetSkImageForSurface(aSurface, &lock);
   if (!image) {
     return;
   }
@@ -654,7 +660,8 @@ DrawTargetSkia::DrawSurfaceWithShadow(SourceSurface *aSurface,
 
   MarkChanged();
 
-  sk_sp<SkImage> image = GetSkImageForSurface(aSurface);
+  Maybe<MutexAutoLock> lock;
+  sk_sp<SkImage> image = GetSkImageForSurface(aSurface, &lock);
   if (!image) {
     return;
   }
@@ -1407,8 +1414,9 @@ DrawTargetSkia::Mask(const Pattern &aSource,
   MarkChanged();
   AutoPaintSetup paint(mCanvas.get(), aOptions, aSource);
 
+  Maybe<MutexAutoLock> lock;
   SkPaint maskPaint;
-  SetPaintPattern(maskPaint, aMask);
+  SetPaintPattern(maskPaint, aMask, lock);
 
   SkLayerRasterizer::Builder builder;
   builder.addLayer(maskPaint);
@@ -1427,7 +1435,8 @@ DrawTargetSkia::MaskSurface(const Pattern &aSource,
   MarkChanged();
   AutoPaintSetup paint(mCanvas.get(), aOptions, aSource, nullptr, -aOffset);
 
-  sk_sp<SkImage> alphaMask = ExtractAlphaForSurface(aMask);
+  Maybe<MutexAutoLock> lock;
+  sk_sp<SkImage> alphaMask = ExtractAlphaForSurface(aMask, lock);
   if (!alphaMask) {
     gfxDebug() << *this << ": MaskSurface() failed to extract alpha for mask";
     return;
@@ -1456,7 +1465,8 @@ DrawTarget::Draw3DTransformedSurface(SourceSurface* aSurface, const Matrix4x4& a
   fullMat.PostTranslate(-xformBounds.x, -xformBounds.y, 0);
 
   // Read in the source data.
-  sk_sp<SkImage> srcImage = GetSkImageForSurface(aSurface);
+  Maybe<MutexAutoLock> lock;
+  sk_sp<SkImage> srcImage = GetSkImageForSurface(aSurface, &lock);
   if (!srcImage) {
     return true;
   }
@@ -1515,7 +1525,8 @@ DrawTargetSkia::Draw3DTransformedSurface(SourceSurface* aSurface, const Matrix4x
 
   MarkChanged();
 
-  sk_sp<SkImage> image = GetSkImageForSurface(aSurface);
+  Maybe<MutexAutoLock> lock;
+  sk_sp<SkImage> image = GetSkImageForSurface(aSurface, &lock);
   if (!image) {
     return true;
   }
@@ -1599,7 +1610,8 @@ already_AddRefed<SourceSurface>
 DrawTargetSkia::OptimizeGPUSourceSurface(SourceSurface *aSurface) const
 {
   // Check if the underlying SkImage already has an associated GrTexture.
-  sk_sp<SkImage> image = GetSkImageForSurface(aSurface);
+  Maybe<MutexAutoLock> lock;
+  sk_sp<SkImage> image = GetSkImageForSurface(aSurface, &lock);
   if (!image || image->isTextureBacked()) {
     RefPtr<SourceSurface> surface(aSurface);
     return surface.forget();
@@ -1716,7 +1728,8 @@ DrawTargetSkia::CopySurface(SourceSurface *aSurface,
 {
   MarkChanged();
 
-  sk_sp<SkImage> image = GetSkImageForSurface(aSurface);
+  Maybe<MutexAutoLock> lock;
+  sk_sp<SkImage> image = GetSkImageForSurface(aSurface, &lock);
   if (!image) {
     return;
   }
@@ -2061,7 +2074,8 @@ DrawTargetSkia::PopLayer()
         paint.setColor(SK_ColorTRANSPARENT);
       }
 
-      sk_sp<SkImage> alphaMask = ExtractAlphaForSurface(layer.mMask);
+      Maybe<MutexAutoLock> lock;
+      sk_sp<SkImage> alphaMask = ExtractAlphaForSurface(layer.mMask, lock);
       if (!alphaMask) {
         gfxDebug() << *this << ": PopLayer() failed to extract alpha for mask";
       } else {
diff --git a/gfx/2d/SourceSurfaceSkia.cpp b/gfx/2d/SourceSurfaceSkia.cpp
index 14cbf6a84..0738f3d39 100644
--- a/gfx/2d/SourceSurfaceSkia.cpp
+++ b/gfx/2d/SourceSurfaceSkia.cpp
@@ -40,6 +40,25 @@ SourceSurfaceSkia::GetFormat() const
   return mFormat;
 }
 
+sk_sp<SkImage>
+SourceSurfaceSkia::GetImage(Maybe<MutexAutoLock>* aLock) {
+  // If we were provided a lock object, we can let the caller access
+  // a shared SkImage and we know it won't go away while the lock is held.
+  if (aLock) {
+    // We are locked, so now we can check mDrawTarget.
+    // If it's null, then we're not shared and we can unlock eagerly.
+    if (!mDrawTarget) {
+      aLock->reset();
+    }
+  } else {
+    // Otherwise we need to call DrawTargetWillChange to ensure we have our
+    // own copy of the SkImage.
+    DrawTargetWillChange();
+  }
+  sk_sp<SkImage> image = mImage;
+  return image;
+}
+  
 static sk_sp<SkData>
 MakeSkData(unsigned char* aData, const IntSize& aSize, int32_t aStride)
 {
diff --git a/gfx/2d/SourceSurfaceSkia.h b/gfx/2d/SourceSurfaceSkia.h
index a91ae93ed..ffb8e47bf 100644
--- a/gfx/2d/SourceSurfaceSkia.h
+++ b/gfx/2d/SourceSurfaceSkia.h
@@ -10,6 +10,10 @@
 #include <vector>
 #include "skia/include/core/SkCanvas.h"
 #include "skia/include/core/SkImage.h"
+#include "mozilla/Maybe.h"
+#include "mozilla/Mutex.h"
+
+typedef mozilla::MutexAutoLock MutexAutoLock;
 
 namespace mozilla {
 
@@ -28,7 +32,7 @@ public:
   virtual IntSize GetSize() const;
   virtual SurfaceFormat GetFormat() const;
 
-  sk_sp<SkImage>& GetImage() { return mImage; }
+  sk_sp<SkImage> GetImage(Maybe<MutexAutoLock>* aLock);
 
   bool InitFromData(unsigned char* aData,
                     const IntSize &aSize,