Bug 1272600 - Part 8 - Simplify the textures ReadLock on the content side. r=sotaro

gfx/layers/client/TextureClient.cpp

@@ -452,13 +452,7 @@ TextureClient::UnlockActor() const
 bool
 TextureClient::IsReadLocked() const
 {
-  // mPendingReadUnlock is true when the texture has been written into (and as 
+  return mReadLock && mReadLock->GetReadCount() > 1;
-  // a result the read-count already incremented on the behalf of the compositor),
-  // but we haven't sent the notification for the compositor to use the texture,
-  // so it is still OK to access the texture data on this side.
-  // If we didn't take mPendingReadUnlock into account here, we would not be able
-  // to Lock and Unlock a texture twice before sending it.
-  return mReadLock && mReadLock->GetReadCount() > 1 && !mPendingReadUnlock;
 }
 
 bool
@@ -535,12 +529,7 @@ TextureClient::Unlock()
   }
 
   if (mOpenMode & OpenMode::OPEN_WRITE) {
-    if (mReadLock && !mPendingReadUnlock) {
+    mUpdated = true;
-      // Take a read lock on behalf of the TextureHost. The latter will unlock
-      // after the shared data is available again for drawing.
-      mReadLock->ReadLock();
-    }
-    mPendingReadUnlock = true;
   }
 
   mData->Unlock();
@@ -555,27 +544,18 @@ TextureClient::EnableReadLock()
 {
   if (!mReadLock) {
     mReadLock = TextureReadLock::Create(mAllocator);
-    if (mPendingReadUnlock) {
-      // We would have done this during TextureClient::Unlock if the ReadLock
-      // had been there, need to account for this here.
-      mReadLock->ReadLock();
-    }
   }
 }
 
-void
-TextureClient::SetReadLock(TextureReadLock* aLock)
-{
-  MOZ_ASSERT(!mReadLock);
-  mReadLock = aLock;
-}
-
 void
 TextureClient::SerializeReadLock(ReadLockDescriptor& aDescriptor)
 {
-  if (mReadLock && mPendingReadUnlock) {
+  if (mReadLock && mUpdated) {
+    // Take a read lock on behalf of the TextureHost. The latter will unlock
+    // after the shared data is available again for drawing.
+    mReadLock->ReadLock();
     mReadLock->Serialize(aDescriptor);
-    mPendingReadUnlock = false;
+    mUpdated = false;
   } else {
     aDescriptor = null_t();
   }
@@ -583,10 +563,7 @@ TextureClient::SerializeReadLock(ReadLockDescriptor& aDescriptor)
 
 TextureClient::~TextureClient()
 {
-  if (mPendingReadUnlock && mReadLock) {
+  mReadLock = nullptr;
-    mReadLock->ReadUnlock();
-    mReadLock = nullptr;
-  }
   Destroy(false);
 }
 
@@ -1094,7 +1071,7 @@ TextureClient::TextureClient(TextureData* aData, TextureFlags aFlags, ClientIPCA
 , mExpectedDtRefs(0)
 #endif
 , mIsLocked(false)
-, mPendingReadUnlock(false)
+, mUpdated(false)
 , mInUse(false)
 , mAddedToCompositableClient(false)
 , mWorkaroundAnnoyingSharedSurfaceLifetimeIssues(false)

gfx/layers/client/TextureClient.h

@@ -653,8 +653,6 @@ public:
 
   void EnableReadLock();
 
-  void SetReadLock(TextureReadLock* aLock);
-
   TextureReadLock* GetReadLock() { return mReadLock; }
 
   bool IsReadLocked() const;
@@ -710,10 +708,10 @@ protected:
   uint32_t mExpectedDtRefs;
 #endif
   bool mIsLocked;
-  // True when there has been a modification of the texture that hasn't been sent
+  // This member tracks that the texture was written into until the update
-  // to the compositor yet. We keep track of this to avoid sending the texture's
+  // is sent to the compositor. We need this remember to lock mReadLock on
-  // ReadLock twice after a single update.
+  // behalf of the compositor just before sending the notification.
-  bool mPendingReadUnlock;
+  bool mUpdated;
   bool mInUse;
 
   bool mAddedToCompositableClient;