BufferQueueProducer::queueBuffer may not drop buffers

Enable BufferQueueProducer::setDequeueTimeout retain existing
dropping behavior. Setting negative and zero to setDequeueTimeout will
not change existing dropping behavior.

BufferQueueProducer::setLegacyBufferDrop can disable buffer dropping
behavior of BufferQueueProducer::queueBuffer. If it's disabled, buffers
will not be dropped unless consumer is SurfaceFlinger.

Bug: 130039639
Change-Id: I8432a7ad386836498e632c67953ad49c6be008bb

3 files changed, 21 insertions, 0 deletions

diff --git a/libs/gui/include/gui/BufferQueueCore.h b/libs/gui/include/gui/BufferQueueCore.h
index 0e8028380..9c0ee99b5 100644
--- a/libs/gui/include/gui/BufferQueueCore.h
+++ b/libs/gui/include/gui/BufferQueueCore.h
@@ -226,6 +226,16 @@ private:
     // consumer are controlled by the application.
     bool mDequeueBufferCannotBlock;
 
+    // mQueueBufferCanDrop indicates whether queueBuffer is allowed to drop
+    // buffers in non-async mode. This flag is set during connect when both the
+    // producer and consumer are controlled by application.
+    bool mQueueBufferCanDrop;
+
+    // mLegacyBufferDrop indicates whether mQueueBufferCanDrop is in effect.
+    // If this flag is set mQueueBufferCanDrop is working as explained. If not
+    // queueBuffer will not drop buffers unless consumer is SurfaceFlinger.
+    bool mLegacyBufferDrop;
+
     // mDefaultBufferFormat can be set so it will override the buffer format
     // when it isn't specified in dequeueBuffer.
     PixelFormat mDefaultBufferFormat;
diff --git a/libs/gui/include/gui/BufferQueueProducer.h b/libs/gui/include/gui/BufferQueueProducer.h
index 415e2a616..d2a47a6aa 100644
--- a/libs/gui/include/gui/BufferQueueProducer.h
+++ b/libs/gui/include/gui/BufferQueueProducer.h
@@ -174,6 +174,9 @@ public:
     // See IGraphicBufferProducer::setDequeueTimeout
     virtual status_t setDequeueTimeout(nsecs_t timeout) override;
 
+    // see IGraphicBufferProducer::setLegacyBufferDrop
+    virtual status_t setLegacyBufferDrop(bool drop);
+
     // See IGraphicBufferProducer::getLastQueuedBuffer
     virtual status_t getLastQueuedBuffer(sp<GraphicBuffer>* outBuffer,
             sp<Fence>* outFence, float outTransformMatrix[16]) override;
diff --git a/libs/gui/include/gui/IGraphicBufferProducer.h b/libs/gui/include/gui/IGraphicBufferProducer.h
index 9f7e22bac..3dde8c8c8 100644
--- a/libs/gui/include/gui/IGraphicBufferProducer.h
+++ b/libs/gui/include/gui/IGraphicBufferProducer.h
@@ -592,12 +592,20 @@ public:
     // non-blocking mode and its corresponding spare buffer (which is used to
     // ensure a buffer is always available).
     //
+    // Note well: queueBuffer will stop buffer dropping behavior if timeout is
+    // strictly positive. If timeout is zero or negative, previous buffer
+    // dropping behavior will not be changed.
+    //
     // Return of a value other than NO_ERROR means an error has occurred:
     // * BAD_VALUE - Failure to adjust the number of available slots. This can
     //               happen because of trying to allocate/deallocate the async
     //               buffer.
     virtual status_t setDequeueTimeout(nsecs_t timeout) = 0;
 
+    // Used to enable/disable buffer drop behavior of queueBuffer.
+    // If it's not used, legacy drop behavior will be retained.
+    virtual status_t setLegacyBufferDrop(bool drop);
+
     // Returns the last queued buffer along with a fence which must signal
     // before the contents of the buffer are read. If there are no buffers in
     // the queue, outBuffer will be populated with nullptr and outFence will be