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, 14 insertions, 0 deletions

diff --git a/include/gui/BufferQueueProducer.h b/include/gui/BufferQueueProducer.h
index 8912097..2eeb979 100644
--- a/include/gui/BufferQueueProducer.h
+++ b/include/gui/BufferQueueProducer.h
@@ -96,6 +96,12 @@ public:
     virtual status_t dequeueBuffer(int *outSlot, sp<Fence>* outFence, bool async,
             uint32_t width, uint32_t height, uint32_t format, uint32_t usage);
 
+    // See IGraphicBufferProducer::detachBuffer
+    virtual status_t detachBuffer(int slot);
+
+    // See IGraphicBufferProducer::attachBuffer
+    virtual status_t attachBuffer(int* outSlot, const sp<GraphicBuffer>& buffer);
+
     // queueBuffer returns a filled buffer to the BufferQueue.
     //
     // Additional data is provided in the QueueBufferInput struct.  Notably,
@@ -151,6 +157,14 @@ private:
     // This is required by the IBinder::DeathRecipient interface
     virtual void binderDied(const wp<IBinder>& who);
 
+    // waitForFreeSlotThenRelock finds the oldest slot in the FREE state. It may
+    // block if there are no available slots and we are not in non-blocking
+    // mode (producer and consumer controlled by the application). If it blocks,
+    // it will release mCore->mMutex while blocked so that other operations on
+    // the BufferQueue may succeed.
+    status_t waitForFreeSlotThenRelock(const char* caller, bool async,
+            int* found, status_t* returnFlags) const;
+
     sp<BufferQueueCore> mCore;
 
     // This references mCore->mSlots. Lock mCore->mMutex while accessing.