Add a BufferItem parameter to onFrameAvailable

Passes the BufferItem for the queued buffer to the onFrameAvailable
callback so the consumer can track the BufferQueue's contents. Also
adds an onFrameReplaced callback, which is necessary if the consumer
wants to do anything more than simple queue length tracking.

Bug: 18111837
Change-Id: If9d07229c9b586c668e5f99074e9b63b0468feb0

1 files changed, 10 insertions, 0 deletions

diff --git a/include/gui/BufferQueueProducer.h b/include/gui/BufferQueueProducer.h
index c619a111c7..ed1056a59d 100644
--- a/include/gui/BufferQueueProducer.h
+++ b/include/gui/BufferQueueProducer.h
@@ -203,6 +203,16 @@ private:
     // since the previous buffer might have already been acquired.
     sp<Fence> mLastQueueBufferFence;
 
+    // Take-a-ticket system for ensuring that onFrame* callbacks are called in
+    // the order that frames are queued. While the BufferQueue lock
+    // (mCore->mMutex) is held, a ticket is retained by the producer. After
+    // dropping the BufferQueue lock, the producer must wait on the condition
+    // variable until the current callback ticket matches its retained ticket.
+    Mutex mCallbackMutex;
+    int mNextCallbackTicket; // Protected by mCore->mMutex
+    int mCurrentCallbackTicket; // Protected by mCallbackMutex
+    Condition mCallbackCondition;
+
 }; // class BufferQueueProducer
 
 } // namespace android