Bug 1083101 - Part 1: Allow multiple read maps on DataSourceSurfaces. r=jrmuizel

gfx/2d/2D.h

@@ -19,6 +19,8 @@
 // to be able to hold on to a GLContext.
 #include "mozilla/GenericRefCounted.h"
 
+#include "mozilla/Atomics.h"
+
 // This RefPtr class isn't ideal for usage in Azure, as it doesn't allow T**
 // outparams using the &-operator. But it will have to do as there's no easy
 // solution.
@@ -373,14 +375,15 @@ class DataSourceSurface : public SourceSurface
 public:
   MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(DataSourceSurface, override)
   DataSourceSurface()
-    : mIsMapped(false)
+    : mMapCount(0)
+    , mIsReadMap(false)
   {
   }
 
 #ifdef DEBUG
   virtual ~DataSourceSurface()
   {
-    MOZ_ASSERT(!mIsMapped, "Someone forgot to call Unmap()");
+    MOZ_ASSERT(mMapCount == 0, "Someone forgot to call Unmap()");
   }
 #endif
 
@@ -458,18 +461,22 @@ public:
   /**
    * The caller is responsible for ensuring aMappedSurface is not null.
    */
-  virtual bool Map(MapType, MappedSurface *aMappedSurface)
+  virtual bool Map(MapType aMapType, MappedSurface *aMappedSurface)
   {
     aMappedSurface->mData = GetData();
     aMappedSurface->mStride = Stride();
-    mIsMapped = !!aMappedSurface->mData;
-    return mIsMapped;
+    if (!aMappedSurface->mData) {
+      return false;
+    }
+    mMapCount++;
+    mIsReadMap = aMapType == MapType::READ;
+    return true;
   }
 
   virtual void Unmap()
   {
-    MOZ_ASSERT(mIsMapped);
-    mIsMapped = false;
+    MOZ_ASSERT(mMapCount > 0);
+    mMapCount--;
   }
 
   /**
@@ -479,7 +486,8 @@ public:
   virtual already_AddRefed<DataSourceSurface> GetDataSurface() override;
 
 protected:
-  bool mIsMapped;
+  Atomic<int32_t> mMapCount;
+  DebugOnly<bool> mIsReadMap;
 };
 
 /** This is an abstract object that accepts path segments. */

gfx/2d/SourceSurfaceD2D.cpp

@@ -252,7 +252,8 @@ DataSourceSurfaceD2D::Map(MapType aMapType, MappedSurface *aMappedSurface)
 {
   // DataSourceSurfaces used with the new Map API should not be used with GetData!!
   MOZ_ASSERT(!mMapped);
-  MOZ_ASSERT(!mIsMapped);
+  // Add support for multiple read locks here!
+  MOZ_ASSERT(mMapCount == 0);
 
   if (!mTexture) {
     return false;
@@ -277,19 +278,24 @@ DataSourceSurfaceD2D::Map(MapType aMapType, MappedSurface *aMappedSurface)
     return false;
   }
 
+  if (!map.pData) {
+    return false;
+  }
+
   aMappedSurface->mData = (uint8_t*)map.pData;
   aMappedSurface->mStride = map.RowPitch;
-  mIsMapped = !!aMappedSurface->mData;
 
-  return mIsMapped;
+  mMapCount++;
+  mIsReadMap = aMapType == MapType::READ;
+  return true;
 }
 
 void
 DataSourceSurfaceD2D::Unmap()
 {
-  MOZ_ASSERT(mIsMapped);
+  MOZ_ASSERT(mMapCount > 0);
 
-  mIsMapped = false;
+  mMapCount--;
   mTexture->Unmap(0);
 }
 
@@ -297,10 +303,9 @@ void
 DataSourceSurfaceD2D::EnsureMappedTexture()
 {
   // Do not use GetData() after having used Map!
-  MOZ_ASSERT(!mIsMapped);
+  MOZ_ASSERT(mMapCount == 0);
 
-  if (mMapped ||
-      !mTexture) {
+  if (mMapped || !mTexture) {
     return;
   }
 

gfx/2d/SourceSurfaceD2D1.cpp

@@ -183,7 +183,8 @@ DataSourceSurfaceD2D1::Map(MapType aMapType, MappedSurface *aMappedSurface)
 {
   // DataSourceSurfaces used with the new Map API should not be used with GetData!!
   MOZ_ASSERT(!mMapped);
-  MOZ_ASSERT(!mIsMapped);
+  // XXX - Add support for multiple read maps here!
+  MOZ_ASSERT(mMapCount == 0);
 
   D2D1_MAP_OPTIONS options;
   if (aMapType == MapType::READ) {
@@ -200,16 +201,22 @@ DataSourceSurfaceD2D1::Map(MapType aMapType, MappedSurface *aMappedSurface)
   aMappedSurface->mData = map.bits;
   aMappedSurface->mStride = map.pitch;
 
-  mIsMapped = !!aMappedSurface->mData;
-  return mIsMapped;
+  if (!aMappedSurface->mData) {
+    return false;
+  }
+
+  mMapCount++;
+  mIsReadMap = aMapType == MapType::READ;
+
+  return true;
 }
 
 void
 DataSourceSurfaceD2D1::Unmap()
 {
-  MOZ_ASSERT(mIsMapped);
+  MOZ_ASSERT(mMapCount > 0);
 
-  mIsMapped = false;
+  mMapCount--;
   mBitmap->Unmap();
 }
 
@@ -225,7 +232,7 @@ void
 DataSourceSurfaceD2D1::EnsureMapped()
 {
   // Do not use GetData() after having used Map!
-  MOZ_ASSERT(!mIsMapped);
+  MOZ_ASSERT(mMapCount == 0);
   if (mMapped) {
     return;
   }

gfx/2d/SourceSurfaceD2DTarget.cpp

@@ -255,7 +255,8 @@ DataSourceSurfaceD2DTarget::Map(MapType aMapType, MappedSurface *aMappedSurface)
 {
   // DataSourceSurfaces used with the new Map API should not be used with GetData!!
   MOZ_ASSERT(!mMapped);
-  MOZ_ASSERT(!mIsMapped);
+  // XXX - Add support for multiple readmaps here!
+  MOZ_ASSERT(mMapCount == 0);
 
   if (!mTexture) {
     return false;
@@ -280,19 +281,25 @@ DataSourceSurfaceD2DTarget::Map(MapType aMapType, MappedSurface *aMappedSurface)
     return false;
   }
 
+  if (!aMappedSurface->mData) {
+    return false;
+  }
+
   aMappedSurface->mData = (uint8_t*)map.pData;
   aMappedSurface->mStride = map.RowPitch;
-  mIsMapped = !!aMappedSurface->mData;
 
-  return mIsMapped;
+  mMapCount++;
+  mIsReadMap = aMapType == MapType::READ;
+
+  return true;
 }
 
 void
 DataSourceSurfaceD2DTarget::Unmap()
 {
-  MOZ_ASSERT(mIsMapped);
+  MOZ_ASSERT(mMapCount > 0);
 
-  mIsMapped = false;
+  mMapCount--;
   mTexture->Unmap(0);
 }
 
@@ -300,7 +307,7 @@ void
 DataSourceSurfaceD2DTarget::EnsureMapped()
 {
   // Do not use GetData() after having used Map!
-  MOZ_ASSERT(!mIsMapped);
+  MOZ_ASSERT(mMapCount == 0);
   if (!mMapped) {
     HRESULT hr = mTexture->Map(0, D3D10_MAP_READ, 0, &mMap);
     if (FAILED(hr)) {