BufferQueue: use max acquired buffer count
This change makes BufferQueue derive the min undequeued buffer count from a max
acquired buffer count that is set by the consumer. This value may be set at
any time that a producer is not connected to the BufferQueue rather than at
BufferQueue construction time.
Change-Id: Icf9f1d91ec612a079968ba0a4621deffe48f4e22
diff --git a/include/gui/BufferQueue.h b/include/gui/BufferQueue.h
index 5b68b05..0a95bb3 100644
--- a/include/gui/BufferQueue.h
+++ b/include/gui/BufferQueue.h
@@ -92,13 +92,11 @@
};
- // BufferQueue manages a pool of gralloc memory slots to be used
- // by producers and consumers.
- // allowSynchronousMode specifies whether or not synchronous mode can be
- // enabled.
- // bufferCount sets the minimum number of undequeued buffers for this queue
+ // BufferQueue manages a pool of gralloc memory slots to be used by
+ // producers and consumers. allowSynchronousMode specifies whether or not
+ // synchronous mode can be enabled by the producer. allocator is used to
+ // allocate all the needed gralloc buffers.
BufferQueue(bool allowSynchronousMode = true,
- int bufferCount = MIN_UNDEQUEUED_BUFFERS,
const sp<IGraphicBufferAlloc>& allocator = NULL);
virtual ~BufferQueue();
@@ -257,6 +255,11 @@
// take effect once the client sets the count back to zero.
status_t setDefaultMaxBufferCount(int bufferCount);
+ // setMaxAcquiredBufferCount sets the maximum number of buffers that can
+ // be acquired by the consumer at one time. This call will fail if a
+ // producer is connected to the BufferQueue.
+ status_t setMaxAcquiredBufferCount(int maxAcquiredBuffers);
+
// isSynchronousMode returns whether the SurfaceTexture is currently in
// synchronous mode.
bool isSynchronousMode() const;
@@ -307,12 +310,16 @@
// given the current BufferQueue state.
int getMinMaxBufferCountLocked() const;
+ // getMinUndequeuedBufferCountLocked returns the minimum number of buffers
+ // that must remain in a state other than DEQUEUED.
+ int getMinUndequeuedBufferCountLocked() const;
+
// getMaxBufferCountLocked returns the maximum number of buffers that can
// be allocated at once. This value depends upon the following member
// variables:
//
// mSynchronousMode
- // mMinUndequeuedBuffers
+ // mMaxAcquiredBufferCount
// mDefaultMaxBufferCount
// mOverrideMaxBufferCount
//
@@ -442,9 +449,14 @@
// in requestBuffers() if a width and height of zero is specified.
uint32_t mDefaultHeight;
- // mMinUndequeuedBuffers is a constraint on the number of buffers
- // not dequeued at any time
- int mMinUndequeuedBuffers;
+ // mMaxAcquiredBufferCount is the number of buffers that the consumer may
+ // acquire at one time. It defaults to 1 and can be changed by the
+ // consumer via the setMaxAcquiredBufferCount method, but this may only be
+ // done when no producer is connected to the BufferQueue.
+ //
+ // This value is used to derive the value returned for the
+ // MIN_UNDEQUEUED_BUFFERS query by the producer.
+ int mMaxAcquiredBufferCount;
// mDefaultMaxBufferCount is the default limit on the number of buffers
// that will be allocated at one time. This default limit is set by the