Bug 1936601. r=gfx-reviewers,lsalzman

Differential Revision: https://phabricator.services.mozilla.com/D234803

Author: aosmond

gfx/layers/SourceSurfaceSharedData.cpp

@@ -105,7 +105,9 @@ bool SourceSurfaceSharedDataWrapper::Map(MapType aMapType,
     MutexAutoLock lock(*mHandleLock);
     dataPtr = GetData();
     if (mMapCount == 0) {
-      SharedSurfacesParent::RemoveTracking(this);
+      if (mConsumers > 0) {
+        SharedSurfacesParent::RemoveTracking(this);
+      }
       if (!dataPtr) {
         size_t len = GetAlignedDataLength();
         if (!EnsureMapped(len)) {
@@ -129,7 +131,7 @@ bool SourceSurfaceSharedDataWrapper::Map(MapType aMapType,
 void SourceSurfaceSharedDataWrapper::Unmap() {
   if (mHandleLock) {
     MutexAutoLock lock(*mHandleLock);
-    if (--mMapCount == 0) {
+    if (--mMapCount == 0 && mConsumers > 0) {
       SharedSurfacesParent::AddTracking(this);
     }
   } else {

gfx/layers/SourceSurfaceSharedData.h

@@ -40,12 +40,7 @@ class SourceSurfaceSharedDataWrapper final : public DataSourceSurface {
   MOZ_DECLARE_REFCOUNTED_VIRTUAL_TYPENAME(SourceSurfaceSharedDataWrapper,
                                           override)
 
-  SourceSurfaceSharedDataWrapper()
-      : mStride(0),
-        mConsumers(0),
-        mFormat(SurfaceFormat::UNKNOWN),
-        mCreatorPid(0),
-        mCreatorRef(true) {}
+  SourceSurfaceSharedDataWrapper() = default;
 
   void Init(const IntSize& aSize, int32_t aStride, SurfaceFormat aFormat,
             SharedMemory::Handle aHandle, base::ProcessId aCreatorPid);
@@ -86,10 +81,7 @@ class SourceSurfaceSharedDataWrapper final : public DataSourceSurface {
     return --mConsumers == 0;
   }
 
-  uint32_t GetConsumers() const {
-    MOZ_ASSERT(mConsumers > 0);
-    return mConsumers;
-  }
+  uint32_t GetConsumers() const { return mConsumers; }
 
   bool HasCreatorRef() const { return mCreatorRef; }
 
@@ -113,13 +105,13 @@ class SourceSurfaceSharedDataWrapper final : public DataSourceSurface {
   // Protects mapping and unmapping of mBuf.
   Maybe<Mutex> mHandleLock;
   nsExpirationState mExpirationState;
-  int32_t mStride;
-  uint32_t mConsumers;
+  int32_t mStride = 0;
+  uint32_t mConsumers = 1;
   IntSize mSize;
   RefPtr<SharedMemory> mBuf;
-  SurfaceFormat mFormat;
-  base::ProcessId mCreatorPid;
-  bool mCreatorRef;
+  SurfaceFormat mFormat = SurfaceFormat::UNKNOWN;
+  base::ProcessId mCreatorPid = 0;
+  bool mCreatorRef = true;
 };
 
 /**

gfx/layers/ipc/SharedSurfacesParent.cpp

@@ -200,7 +200,6 @@ void SharedSurfacesParent::AddSameProcess(const wr::ExternalImageId& aId,
   auto texture = MakeRefPtr<wr::RenderSharedSurfaceTextureHost>(surface);
   wr::RenderThread::Get()->RegisterExternalImage(aId, texture.forget());
 
-  surface->AddConsumer();
   sInstance->mSurfaces.InsertOrUpdate(id, std::move(surface));
 }
 
@@ -269,7 +268,6 @@ void SharedSurfacesParent::Add(const wr::ExternalImageId& aId,
   auto texture = MakeRefPtr<wr::RenderSharedSurfaceTextureHost>(surface);
   wr::RenderThread::Get()->RegisterExternalImage(aId, texture.forget());
 
-  surface->AddConsumer();
   sInstance->mSurfaces.InsertOrUpdate(id, std::move(surface));
 }
 
@@ -284,6 +282,7 @@ void SharedSurfacesParent::AddTrackingLocked(
     SourceSurfaceSharedDataWrapper* aSurface,
     const StaticMutexAutoLock& aAutoLock) {
   MOZ_ASSERT(!aSurface->GetExpirationState()->IsTracked());
+  MOZ_ASSERT(aSurface->GetConsumers() > 0);
   sInstance->mTracker.AddObjectLocked(aSurface, aAutoLock);
 }
 
@@ -356,6 +355,7 @@ bool SharedSurfacesParent::AgeAndExpireOneGeneration() {
 void SharedSurfacesParent::ExpireMap(
     nsTArray<RefPtr<SourceSurfaceSharedDataWrapper>>& aExpired) {
   for (auto& surface : aExpired) {
+    MOZ_ASSERT(surface->GetConsumers() > 0);
     surface->ExpireMap();
   }
 }