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Commit ecc50404 authored by Dan Stoza's avatar Dan Stoza
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SurfaceFlinger: Fix PTS on stale buffers 

SurfaceFlinger's (Layer's) shadow copy of the BufferQueue queue was
getting out of sync for a few reasons. This change fixes these by
doing the following:

- Adds a check to re-synchronize the shadow copy every time we
  successfully acquire a buffer by first dropping stale buffers before
  removing the current buffer.
- Avoids trying to perform updates for buffers which have been rejected
  (for incorrect dimensions) by SurfaceFlinger.
- Adds IGraphicBufferConsumer::setShadowQueueSize, which allows the
  consumer to notify the BufferQueue that it is maintaining a shadow
  copy of the queue and prevents it from dropping so many buffers
  during acquireBuffer that it ends up returning a buffer for which the
  consumer has not yet received an onFrameAvailable call.

Bug: 20096136
Change-Id: I78d0738428005fc19b3be85cc8f1db498043612f
(cherry picked from commit 2e36f228)
parent 7b2fc930

include/gui/BufferQueueConsumer.h

+3 −0
Original line number Diff line number Diff line
@@ -148,6 +148,9 @@ public: 
    // Retrieve the sideband buffer stream, if any.

    virtual sp<NativeHandle> getSidebandStream() const;



    // See IGraphicBufferConsumer::setShadowQueueSize

    virtual void setShadowQueueSize(size_t size);



    // dump our state in a String

    virtual void dump(String8& result, const char* prefix) const;

include/gui/BufferQueueCore.h

+7 −0
Original line number Diff line number Diff line
@@ -274,6 +274,13 @@ private: 
    // mBufferAge tracks the age of the contents of the most recently dequeued

    // buffer as the number of frames that have elapsed since it was last queued

    uint64_t mBufferAge;



    // mConsumerHasShadowQueue determines if acquireBuffer should be more

    // cautious about dropping buffers so that it always returns a buffer that

    // is represented in the consumer's shadow queue.

    bool mConsumerHasShadowQueue;

    size_t mConsumerShadowQueueSize;



}; // class BufferQueueCore



} // namespace android

include/gui/IGraphicBufferConsumer.h

+5 −0
Original line number Diff line number Diff line
@@ -248,6 +248,11 @@ public: 
    // Retrieve the sideband buffer stream, if any.

    virtual sp<NativeHandle> getSidebandStream() const = 0;



    // setShadowQueueSize notifies the BufferQueue that the consumer is

    // shadowing its queue and allows it to limit the number of buffers it is

    // permitted to drop during acquire so as to not get out of sync.

    virtual void setShadowQueueSize(size_t size) = 0;



    // dump state into a string

    virtual void dump(String8& result, const char* prefix) const = 0;

libs/gui/BufferQueueConsumer.cpp

+22 −0
Original line number Diff line number Diff line
@@ -89,7 +89,20 @@ status_t BufferQueueConsumer::acquireBuffer(BufferItem* outBuffer, 
        // the timestamps are being auto-generated by Surface. If the app isn't

        // generating timestamps explicitly, it probably doesn't want frames to

        // be discarded based on them.

        //

        // If the consumer is shadowing our queue, we also make sure that we

        // don't drop so many buffers that the consumer hasn't received the

        // onFrameAvailable callback for the buffer it acquires. That is, we

        // want the buffer we return to be in the consumer's shadow queue.

        size_t droppableBuffers = mCore->mConsumerShadowQueueSize > 1 ?

                mCore->mConsumerShadowQueueSize - 1 : 0;

        while (mCore->mQueue.size() > 1 && !mCore->mQueue[0].mIsAutoTimestamp) {

            if (mCore->mConsumerHasShadowQueue && droppableBuffers == 0) {

                BQ_LOGV("acquireBuffer: no droppable buffers in consumer's"

                        " shadow queue, continuing");

                break;

            }



            // If entry[1] is timely, drop entry[0] (and repeat). We apply an

            // additional criterion here: we only drop the earlier buffer if our

            // desiredPresent falls within +/- 1 second of the expected present.
@@ -124,6 +137,7 @@ status_t BufferQueueConsumer::acquireBuffer(BufferItem* outBuffer, 
            }

            mCore->mQueue.erase(front);

            front = mCore->mQueue.begin();

            --droppableBuffers;

        }



        // See if the front buffer is due
@@ -537,6 +551,14 @@ sp<NativeHandle> BufferQueueConsumer::getSidebandStream() const { 
    return mCore->mSidebandStream;

}



void BufferQueueConsumer::setShadowQueueSize(size_t size) {

    ATRACE_CALL();

    BQ_LOGV("setShadowQueueSize: %zu", size);

    Mutex::Autolock lock(mCore->mMutex);

    mCore->mConsumerHasShadowQueue = true;

    mCore->mConsumerShadowQueueSize = size;

}



void BufferQueueConsumer::dump(String8& result, const char* prefix) const {

    mCore->dump(result, prefix);

}

libs/gui/BufferQueueCore.cpp

+3 −1
Original line number Diff line number Diff line
@@ -71,7 +71,9 @@ BufferQueueCore::BufferQueueCore(const sp<IGraphicBufferAlloc>& allocator) : 
    mIsAllocating(false),

    mIsAllocatingCondition(),

    mAllowAllocation(true),

    mBufferAge(0)

    mBufferAge(0),

    mConsumerHasShadowQueue(false),

    mConsumerShadowQueueSize(0)

{

    if (allocator == NULL) {

        sp<ISurfaceComposer> composer(ComposerService::getComposerService());