Pass the IGraphicBufferAlloc to SurfaceTextureClient.

This change passes a reference to the IGraphicBufferAlloc binder object
to SurfaceTextureClient objects.  When STC objects are created they
query their associated ISurfaceTexture object for the
IGraphicBufferAlloc that the SurfaceTexture uses to allocate buffers.
Having the SurfaceTextureClient hold this reference prevents the
GraphicBufferAlloc in SurfaceFlinger from freeing the allocated buffers
before the SurfaceTextureClient is done with them.

Change-Id: Ib8e30e8b37fdd60438cbb4cb7e9174d0ba6d661c
related-bug: 3362519

3 files changed, 16 insertions, 0 deletions

diff --git a/include/gui/ISurfaceTexture.h b/include/gui/ISurfaceTexture.h
index 77d37f1..168310c 100644
--- a/include/gui/ISurfaceTexture.h
+++ b/include/gui/ISurfaceTexture.h
@@ -72,6 +72,12 @@ public:
 
     virtual status_t setCrop(const Rect& reg) = 0;
     virtual status_t setTransform(uint32_t transform) = 0;
+
+    // getAllocator retrieves the binder object that must be referenced as long
+    // as the GraphicBuffers dequeued from this ISurfaceTexture are referenced.
+    // Holding this binder reference prevents SurfaceFlinger from freeing the
+    // buffers before the client is done with them.
+    virtual sp<IBinder> getAllocator() = 0;
 };
 
 // ----------------------------------------------------------------------------
diff --git a/include/gui/SurfaceTexture.h b/include/gui/SurfaceTexture.h
index 79c33f5..31615d0 100644
--- a/include/gui/SurfaceTexture.h
+++ b/include/gui/SurfaceTexture.h
@@ -101,6 +101,12 @@ public:
     // when a new frame becomes available.
     void setFrameAvailableListener(const sp<FrameAvailableListener>& l);
 
+    // getAllocator retrieves the binder object that must be referenced as long
+    // as the GraphicBuffers dequeued from this SurfaceTexture are referenced.
+    // Holding this binder reference prevents SurfaceFlinger from freeing the
+    // buffers before the client is done with them.
+    sp<IBinder> getAllocator();
+
 private:
 
     // freeAllBuffers frees the resources (both GraphicBuffer and EGLImage) for
diff --git a/include/gui/SurfaceTextureClient.h b/include/gui/SurfaceTextureClient.h
index dd1d490..ff2251d 100644
--- a/include/gui/SurfaceTextureClient.h
+++ b/include/gui/SurfaceTextureClient.h
@@ -83,6 +83,10 @@ private:
     // interactions with the server using this interface.
     sp<ISurfaceTexture> mSurfaceTexture;
 
+    // mAllocator is the binder object that is referenced to prevent the
+    // dequeued buffers from being freed prematurely.
+    sp<IBinder> mAllocator;
+
     // mSlots stores the buffers that have been allocated for each buffer slot.
     // It is initialized to null pointers, and gets filled in with the result of
     // ISurfaceTexture::requestBuffer when the client dequeues a buffer from a