BufferQueue: Allow detaching/reattaching buffers

Adds detachBuffer and attachBuffer calls to both the producer and
consumer sides of BufferQueue. Buffers may be detached while dequeued
by the producer or acquired by the consumer, and when attached, enter
the dequeued and acquired states, respectively.

Bug: 13173343
Change-Id: Ic152692b0a94d99e0135b9bfa62747dab2a54220

1 files changed, 7 insertions, 1 deletions

diff --git a/include/gui/BufferSlot.h b/include/gui/BufferSlot.h
index 2c4b43f..6085e11 100644
--- a/include/gui/BufferSlot.h
+++ b/include/gui/BufferSlot.h
@@ -38,7 +38,8 @@ struct BufferSlot {
       mFrameNumber(0),
       mEglFence(EGL_NO_SYNC_KHR),
       mAcquireCalled(false),
-      mNeedsCleanupOnRelease(false) {
+      mNeedsCleanupOnRelease(false),
+      mAttachedByConsumer(false) {
     }
 
     // mGraphicBuffer points to the buffer allocated for this slot or is NULL
@@ -129,6 +130,11 @@ struct BufferSlot {
     // consumer.  This is set when a buffer in ACQUIRED state is freed.
     // It causes releaseBuffer to return STALE_BUFFER_SLOT.
     bool mNeedsCleanupOnRelease;
+
+    // Indicates whether the buffer was attached on the consumer side.
+    // If so, it needs to set the BUFFER_NEEDS_REALLOCATION flag when dequeued
+    // to prevent the producer from using a stale cached buffer.
+    bool mAttachedByConsumer;
 };
 
 } // namespace android