services/surfaceflinger/BufferQueueLayer.cpp - android_frameworks_native - Gitiles

 /*
  * Copyright (C) 2018 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #include <compositionengine/Display.h>
 #include <compositionengine/Layer.h>
 #include <compositionengine/OutputLayer.h>
 #include <compositionengine/impl/LayerCompositionState.h>
 #include <compositionengine/impl/OutputLayerCompositionState.h>
 #include <system/window.h>

 #include "BufferQueueLayer.h"
 #include "LayerRejecter.h"
 #include "SurfaceInterceptor.h"

 #include "TimeStats/TimeStats.h"

 namespace android {

 BufferQueueLayer::BufferQueueLayer(const LayerCreationArgs& args) : BufferLayer(args) {}

 BufferQueueLayer::~BufferQueueLayer() {
     mConsumer->abandon();
 }

 // -----------------------------------------------------------------------
 // Interface implementation for Layer
 // -----------------------------------------------------------------------

 void BufferQueueLayer::onLayerDisplayed(const sp<Fence>& releaseFence) {
     mConsumer->setReleaseFence(releaseFence);
 }

 void BufferQueueLayer::setTransformHint(uint32_t orientation) const {
     mConsumer->setTransformHint(orientation);
 }

 std::vector<OccupancyTracker::Segment> BufferQueueLayer::getOccupancyHistory(bool forceFlush) {
     std::vector<OccupancyTracker::Segment> history;
     status_t result = mConsumer->getOccupancyHistory(forceFlush, &history);
     if (result != NO_ERROR) {
         ALOGW("[%s] Failed to obtain occupancy history (%d)", mName.string(), result);
         return {};
     }
     return history;
 }

 bool BufferQueueLayer::getTransformToDisplayInverse() const {
     return mConsumer->getTransformToDisplayInverse();
 }

 void BufferQueueLayer::releasePendingBuffer(nsecs_t dequeueReadyTime) {
     if (!mConsumer->releasePendingBuffer()) {
         return;
     }

     auto releaseFenceTime = std::make_shared<FenceTime>(mConsumer->getPrevFinalReleaseFence());
     mReleaseTimeline.updateSignalTimes();
     mReleaseTimeline.push(releaseFenceTime);

     Mutex::Autolock lock(mFrameEventHistoryMutex);
     if (mPreviousFrameNumber != 0) {
         mFrameEventHistory.addRelease(mPreviousFrameNumber, dequeueReadyTime,
                                       std::move(releaseFenceTime));
     }
 }

 void BufferQueueLayer::setDefaultBufferSize(uint32_t w, uint32_t h) {
     mConsumer->setDefaultBufferSize(w, h);
 }

 int32_t BufferQueueLayer::getQueuedFrameCount() const {
     return mQueuedFrames;
 }

 bool BufferQueueLayer::shouldPresentNow(nsecs_t expectedPresentTime) const {
     if (getSidebandStreamChanged() || getAutoRefresh()) {
         return true;
     }

     if (!hasFrameUpdate()) {
         return false;
     }

     Mutex::Autolock lock(mQueueItemLock);

     const int64_t addedTime = mQueueItems[0].mTimestamp;

     // Ignore timestamps more than a second in the future
     const bool isPlausible = addedTime < (expectedPresentTime + s2ns(1));
     ALOGW_IF(!isPlausible,
              "[%s] Timestamp %" PRId64 " seems implausible "
              "relative to expectedPresent %" PRId64,
              mName.string(), addedTime, expectedPresentTime);

     const bool isDue = addedTime < expectedPresentTime;
     return isDue || !isPlausible;
 }

 // -----------------------------------------------------------------------
 // Interface implementation for BufferLayer
 // -----------------------------------------------------------------------

 bool BufferQueueLayer::fenceHasSignaled() const {
     if (latchUnsignaledBuffers()) {
         return true;
     }

     if (!hasFrameUpdate()) {
         return true;
     }

     Mutex::Autolock lock(mQueueItemLock);
     if (mQueueItems[0].mIsDroppable) {
         // Even though this buffer's fence may not have signaled yet, it could
         // be replaced by another buffer before it has a chance to, which means
         // that it's possible to get into a situation where a buffer is never
         // able to be latched. To avoid this, grab this buffer anyway.
         return true;
     }
     return mQueueItems[0].mFenceTime->getSignalTime() != Fence::SIGNAL_TIME_PENDING;
 }

 nsecs_t BufferQueueLayer::getDesiredPresentTime() {
     return mConsumer->getTimestamp();
 }

 std::shared_ptr<FenceTime> BufferQueueLayer::getCurrentFenceTime() const {
     return mConsumer->getCurrentFenceTime();
 }

 void BufferQueueLayer::getDrawingTransformMatrix(float *matrix) {
     return mConsumer->getTransformMatrix(matrix);
 }

 // NOTE: SurfaceFlinger's definitions of "Current" and "Drawing" do not neatly map to BufferQueue's
 // These functions get the fields for the frame that is currently in SurfaceFlinger's Drawing state
 // so the functions start with "getDrawing". The data is retrieved from the BufferQueueConsumer's
 // current buffer so the consumer functions start with "getCurrent".
 //
 // This results in the rather confusing functions below.
 uint32_t BufferQueueLayer::getDrawingTransform() const {
     return mConsumer->getCurrentTransform();
 }

 ui::Dataspace BufferQueueLayer::getDrawingDataSpace() const {
     return mConsumer->getCurrentDataSpace();
 }

 Rect BufferQueueLayer::getDrawingCrop() const {
     return mConsumer->getCurrentCrop();
 }

 uint32_t BufferQueueLayer::getDrawingScalingMode() const {
     return mConsumer->getCurrentScalingMode();
 }

 Region BufferQueueLayer::getDrawingSurfaceDamage() const {
     return mConsumer->getSurfaceDamage();
 }

 const HdrMetadata& BufferQueueLayer::getDrawingHdrMetadata() const {
     return mConsumer->getCurrentHdrMetadata();
 }

 int BufferQueueLayer::getDrawingApi() const {
     return mConsumer->getCurrentApi();
 }

 PixelFormat BufferQueueLayer::getPixelFormat() const {
     return mFormat;
 }

 uint64_t BufferQueueLayer::getFrameNumber() const {
     Mutex::Autolock lock(mQueueItemLock);
     return mQueueItems[0].mFrameNumber;
 }

 bool BufferQueueLayer::getAutoRefresh() const {
     return mAutoRefresh;
 }

 bool BufferQueueLayer::getSidebandStreamChanged() const {
     return mSidebandStreamChanged;
 }

 bool BufferQueueLayer::latchSidebandStream(bool& recomputeVisibleRegions) {
     bool sidebandStreamChanged = true;
     if (mSidebandStreamChanged.compare_exchange_strong(sidebandStreamChanged, false)) {
         // mSidebandStreamChanged was changed to false
         auto& layerCompositionState = getCompositionLayer()->editState().frontEnd;
         layerCompositionState.sidebandStream = mConsumer->getSidebandStream();
         if (layerCompositionState.sidebandStream != nullptr) {
             setTransactionFlags(eTransactionNeeded);
             mFlinger->setTransactionFlags(eTraversalNeeded);
         }
         recomputeVisibleRegions = true;

         return true;
     }
     return false;
 }

 bool BufferQueueLayer::hasFrameUpdate() const {
     return mQueuedFrames > 0;
 }

 void BufferQueueLayer::setFilteringEnabled(bool enabled) {
     return mConsumer->setFilteringEnabled(enabled);
 }

 status_t BufferQueueLayer::bindTextureImage() {
     return mConsumer->bindTextureImage();
 }

 status_t BufferQueueLayer::updateTexImage(bool& recomputeVisibleRegions, nsecs_t latchTime) {
     // This boolean is used to make sure that SurfaceFlinger's shadow copy
     // of the buffer queue isn't modified when the buffer queue is returning
     // BufferItem's that weren't actually queued. This can happen in shared
     // buffer mode.
     bool queuedBuffer = false;
     const int32_t layerID = getSequence();
     LayerRejecter r(mDrawingState, getCurrentState(), recomputeVisibleRegions,
                     getProducerStickyTransform() != 0, mName.string(), mOverrideScalingMode,
                     getTransformToDisplayInverse(), mFreezeGeometryUpdates);

     nsecs_t expectedPresentTime = mFlinger->mScheduler->expectedPresentTime();

     if (isRemovedFromCurrentState()) {
         expectedPresentTime = 0;
     }

     // updateTexImage() below might drop the some buffers at the head of the queue if there is a
     // buffer behind them which is timely to be presented. However this buffer may not be signaled
     // yet. The code below makes sure that this wouldn't happen by setting maxFrameNumber to the
     // last buffer that was signaled.
     uint64_t lastSignaledFrameNumber = mLastFrameNumberReceived;
     {
         Mutex::Autolock lock(mQueueItemLock);
         for (int i = 0; i < mQueueItems.size(); i++) {
             bool fenceSignaled =
                     mQueueItems[i].mFenceTime->getSignalTime() != Fence::SIGNAL_TIME_PENDING;
             if (!fenceSignaled) {
                 break;
             }
             lastSignaledFrameNumber = mQueueItems[i].mFrameNumber;
         }
     }
     const uint64_t maxFrameNumberToAcquire =
             std::min(mLastFrameNumberReceived.load(), lastSignaledFrameNumber);

     status_t updateResult = mConsumer->updateTexImage(&r, expectedPresentTime, &mAutoRefresh,
                                                       &queuedBuffer, maxFrameNumberToAcquire);
     if (updateResult == BufferQueue::PRESENT_LATER) {
         // Producer doesn't want buffer to be displayed yet.  Signal a
         // layer update so we check again at the next opportunity.
         mFlinger->signalLayerUpdate();
         return BAD_VALUE;
     } else if (updateResult == BufferLayerConsumer::BUFFER_REJECTED) {
         // If the buffer has been rejected, remove it from the shadow queue
         // and return early
         if (queuedBuffer) {
             Mutex::Autolock lock(mQueueItemLock);
             mFlinger->mTimeStats->removeTimeRecord(layerID, mQueueItems[0].mFrameNumber);
             mQueueItems.removeAt(0);
             mQueuedFrames--;
         }
         return BAD_VALUE;
     } else if (updateResult != NO_ERROR || mUpdateTexImageFailed) {
         // This can occur if something goes wrong when trying to create the
         // EGLImage for this buffer. If this happens, the buffer has already
         // been released, so we need to clean up the queue and bug out
         // early.
         if (queuedBuffer) {
             Mutex::Autolock lock(mQueueItemLock);
             mQueueItems.clear();
             mQueuedFrames = 0;
             mFlinger->mTimeStats->onDestroy(layerID);
         }

         // Once we have hit this state, the shadow queue may no longer
         // correctly reflect the incoming BufferQueue's contents, so even if
         // updateTexImage starts working, the only safe course of action is
         // to continue to ignore updates.
         mUpdateTexImageFailed = true;

         return BAD_VALUE;
     }

     if (queuedBuffer) {
         // Autolock scope
         auto currentFrameNumber = mConsumer->getFrameNumber();

         Mutex::Autolock lock(mQueueItemLock);

         // Remove any stale buffers that have been dropped during
         // updateTexImage
         while (mQueueItems[0].mFrameNumber != currentFrameNumber) {
             mFlinger->mTimeStats->removeTimeRecord(layerID, mQueueItems[0].mFrameNumber);
             mQueueItems.removeAt(0);
             mQueuedFrames--;
         }

         mFlinger->mTimeStats->setAcquireFence(layerID, currentFrameNumber,
                                               mQueueItems[0].mFenceTime);
         mFlinger->mTimeStats->setLatchTime(layerID, currentFrameNumber, latchTime);

         mQueueItems.removeAt(0);
     }

     // Decrement the queued-frames count.  Signal another event if we
     // have more frames pending.
     if ((queuedBuffer && mQueuedFrames.fetch_sub(1) > 1) || mAutoRefresh) {
         mFlinger->signalLayerUpdate();
     }

     return NO_ERROR;
 }

 status_t BufferQueueLayer::updateActiveBuffer() {
     // update the active buffer
     mActiveBuffer = mConsumer->getCurrentBuffer(&mActiveBufferSlot, &mActiveBufferFence);
     auto& layerCompositionState = getCompositionLayer()->editState().frontEnd;
     layerCompositionState.buffer = mActiveBuffer;
     layerCompositionState.bufferSlot = mActiveBufferSlot;

     if (mActiveBuffer == nullptr) {
         // this can only happen if the very first buffer was rejected.
         return BAD_VALUE;
     }
     return NO_ERROR;
 }

 status_t BufferQueueLayer::updateFrameNumber(nsecs_t latchTime) {
     mPreviousFrameNumber = mCurrentFrameNumber;
     mCurrentFrameNumber = mConsumer->getFrameNumber();

     {
         Mutex::Autolock lock(mFrameEventHistoryMutex);
         mFrameEventHistory.addLatch(mCurrentFrameNumber, latchTime);
     }
     return NO_ERROR;
 }

 void BufferQueueLayer::setHwcLayerBuffer(const sp<const DisplayDevice>& display) {
     const auto outputLayer = findOutputLayerForDisplay(display);
     LOG_FATAL_IF(!outputLayer);
     LOG_FATAL_IF(!outputLayer->getState.hwc);
     auto& hwcLayer = (*outputLayer->getState().hwc).hwcLayer;

     uint32_t hwcSlot = 0;
     sp<GraphicBuffer> hwcBuffer;

     // INVALID_BUFFER_SLOT is used to identify BufferStateLayers.  Default to 0
     // for BufferQueueLayers
     int slot = (mActiveBufferSlot == BufferQueue::INVALID_BUFFER_SLOT) ? 0 : mActiveBufferSlot;
     (*outputLayer->editState().hwc)
             .hwcBufferCache.getHwcBuffer(slot, mActiveBuffer, &hwcSlot, &hwcBuffer);

     auto acquireFence = mConsumer->getCurrentFence();
     auto error = hwcLayer->setBuffer(hwcSlot, hwcBuffer, acquireFence);
     if (error != HWC2::Error::None) {
         ALOGE("[%s] Failed to set buffer %p: %s (%d)", mName.string(), mActiveBuffer->handle,
               to_string(error).c_str(), static_cast<int32_t>(error));
     }

     auto& layerCompositionState = getCompositionLayer()->editState().frontEnd;
     layerCompositionState.bufferSlot = mActiveBufferSlot;
     layerCompositionState.buffer = mActiveBuffer;
     layerCompositionState.acquireFence = acquireFence;
 }

 // -----------------------------------------------------------------------
 // Interface implementation for BufferLayerConsumer::ContentsChangedListener
 // -----------------------------------------------------------------------

 void BufferQueueLayer::fakeVsync() {
     mRefreshPending = false;
     bool ignored = false;
     latchBuffer(ignored, systemTime());
     usleep(16000);
     releasePendingBuffer(systemTime());
 }

 void BufferQueueLayer::onFrameAvailable(const BufferItem& item) {
     // Add this buffer from our internal queue tracker
     { // Autolock scope
         if (mFlinger->mUseSmart90ForVideo) {
             // Report mApi ID for each layer.
             mFlinger->mScheduler->addNativeWindowApi(item.mApi);
         }

         Mutex::Autolock lock(mQueueItemLock);
         // Reset the frame number tracker when we receive the first buffer after
         // a frame number reset
         if (item.mFrameNumber == 1) {
             mLastFrameNumberReceived = 0;
         }

         // Ensure that callbacks are handled in order
         while (item.mFrameNumber != mLastFrameNumberReceived + 1) {
             status_t result = mQueueItemCondition.waitRelative(mQueueItemLock, ms2ns(500));
             if (result != NO_ERROR) {
                 ALOGE("[%s] Timed out waiting on callback", mName.string());
             }
         }

         mQueueItems.push_back(item);
         mQueuedFrames++;

         // Wake up any pending callbacks
         mLastFrameNumberReceived = item.mFrameNumber;
         mQueueItemCondition.broadcast();
     }

     mFlinger->mInterceptor->saveBufferUpdate(this, item.mGraphicBuffer->getWidth(),
                                              item.mGraphicBuffer->getHeight(), item.mFrameNumber);

     // If this layer is orphaned, then we run a fake vsync pulse so that
     // dequeueBuffer doesn't block indefinitely.
     if (isRemovedFromCurrentState()) {
         fakeVsync();
     } else {
         mFlinger->signalLayerUpdate();
     }
 }

 void BufferQueueLayer::onFrameReplaced(const BufferItem& item) {
     { // Autolock scope
         Mutex::Autolock lock(mQueueItemLock);

         // Ensure that callbacks are handled in order
         while (item.mFrameNumber != mLastFrameNumberReceived + 1) {
             status_t result = mQueueItemCondition.waitRelative(mQueueItemLock, ms2ns(500));
             if (result != NO_ERROR) {
                 ALOGE("[%s] Timed out waiting on callback", mName.string());
             }
         }

         if (!hasFrameUpdate()) {
             ALOGE("Can't replace a frame on an empty queue");
             return;
         }
         mQueueItems.editItemAt(mQueueItems.size() - 1) = item;

         // Wake up any pending callbacks
         mLastFrameNumberReceived = item.mFrameNumber;
         mQueueItemCondition.broadcast();
     }
 }

 void BufferQueueLayer::onSidebandStreamChanged() {
     bool sidebandStreamChanged = false;
     if (mSidebandStreamChanged.compare_exchange_strong(sidebandStreamChanged, true)) {
         // mSidebandStreamChanged was changed to true
         mFlinger->signalLayerUpdate();
     }
 }

 // -----------------------------------------------------------------------

 void BufferQueueLayer::onFirstRef() {
     BufferLayer::onFirstRef();

     // Creates a custom BufferQueue for SurfaceFlingerConsumer to use
     sp<IGraphicBufferProducer> producer;
     sp<IGraphicBufferConsumer> consumer;
     BufferQueue::createBufferQueue(&producer, &consumer, true);
     mProducer = new MonitoredProducer(producer, mFlinger, this);
     {
         // Grab the SF state lock during this since it's the only safe way to access RenderEngine
         Mutex::Autolock lock(mFlinger->mStateLock);
         mConsumer =
                 new BufferLayerConsumer(consumer, mFlinger->getRenderEngine(), mTextureName, this);
     }
     mConsumer->setConsumerUsageBits(getEffectiveUsage(0));
     mConsumer->setContentsChangedListener(this);
     mConsumer->setName(mName);

     // BufferQueueCore::mMaxDequeuedBufferCount is default to 1
     if (!mFlinger->isLayerTripleBufferingDisabled()) {
         mProducer->setMaxDequeuedBufferCount(2);
     }

     if (const auto display = mFlinger->getDefaultDisplayDevice()) {
         updateTransformHint(display);
     }
 }

 status_t BufferQueueLayer::setDefaultBufferProperties(uint32_t w, uint32_t h, PixelFormat format) {
     uint32_t const maxSurfaceDims =
           std::min(mFlinger->getMaxTextureSize(), mFlinger->getMaxViewportDims());

     // never allow a surface larger than what our underlying GL implementation
     // can handle.
     if ((uint32_t(w) > maxSurfaceDims) || (uint32_t(h) > maxSurfaceDims)) {
         ALOGE("dimensions too large %u x %u", uint32_t(w), uint32_t(h));
         return BAD_VALUE;
     }

     mFormat = format;

     setDefaultBufferSize(w, h);
     mConsumer->setDefaultBufferFormat(format);
     mConsumer->setConsumerUsageBits(getEffectiveUsage(0));

     return NO_ERROR;
 }

 sp<IGraphicBufferProducer> BufferQueueLayer::getProducer() const {
     return mProducer;
 }

 uint32_t BufferQueueLayer::getProducerStickyTransform() const {
     int producerStickyTransform = 0;
     int ret = mProducer->query(NATIVE_WINDOW_STICKY_TRANSFORM, &producerStickyTransform);
     if (ret != OK) {
         ALOGW("%s: Error %s (%d) while querying window sticky transform.", __FUNCTION__,
               strerror(-ret), ret);
         return 0;
     }
     return static_cast<uint32_t>(producerStickyTransform);
 }

 } // namespace android
	/*
	* Copyright (C) 2018 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#include <compositionengine/Display.h>
	#include <compositionengine/Layer.h>
	#include <compositionengine/OutputLayer.h>
	#include <compositionengine/impl/LayerCompositionState.h>
	#include <compositionengine/impl/OutputLayerCompositionState.h>
	#include <system/window.h>

	#include "BufferQueueLayer.h"
	#include "LayerRejecter.h"
	#include "SurfaceInterceptor.h"

	#include "TimeStats/TimeStats.h"

	namespace android {

	BufferQueueLayer::BufferQueueLayer(const LayerCreationArgs& args) : BufferLayer(args) {}

	BufferQueueLayer::~BufferQueueLayer() {
	mConsumer->abandon();
	}

	// -----------------------------------------------------------------------
	// Interface implementation for Layer
	// -----------------------------------------------------------------------

	void BufferQueueLayer::onLayerDisplayed(const sp<Fence>& releaseFence) {
	mConsumer->setReleaseFence(releaseFence);
	}

	void BufferQueueLayer::setTransformHint(uint32_t orientation) const {
	mConsumer->setTransformHint(orientation);
	}

	std::vector<OccupancyTracker::Segment> BufferQueueLayer::getOccupancyHistory(bool forceFlush) {
	std::vector<OccupancyTracker::Segment> history;
	status_t result = mConsumer->getOccupancyHistory(forceFlush, &history);
	if (result != NO_ERROR) {
	ALOGW("[%s] Failed to obtain occupancy history (%d)", mName.string(), result);
	return {};
	}
	return history;
	}

	bool BufferQueueLayer::getTransformToDisplayInverse() const {
	return mConsumer->getTransformToDisplayInverse();
	}

	void BufferQueueLayer::releasePendingBuffer(nsecs_t dequeueReadyTime) {
	if (!mConsumer->releasePendingBuffer()) {
	return;
	}

	auto releaseFenceTime = std::make_shared<FenceTime>(mConsumer->getPrevFinalReleaseFence());
	mReleaseTimeline.updateSignalTimes();
	mReleaseTimeline.push(releaseFenceTime);

	Mutex::Autolock lock(mFrameEventHistoryMutex);
	if (mPreviousFrameNumber != 0) {
	mFrameEventHistory.addRelease(mPreviousFrameNumber, dequeueReadyTime,
	std::move(releaseFenceTime));
	}
	}

	void BufferQueueLayer::setDefaultBufferSize(uint32_t w, uint32_t h) {
	mConsumer->setDefaultBufferSize(w, h);
	}

	int32_t BufferQueueLayer::getQueuedFrameCount() const {
	return mQueuedFrames;
	}

	bool BufferQueueLayer::shouldPresentNow(nsecs_t expectedPresentTime) const {
	if (getSidebandStreamChanged() \|\| getAutoRefresh()) {
	return true;
	}

	if (!hasFrameUpdate()) {
	return false;
	}

	Mutex::Autolock lock(mQueueItemLock);

	const int64_t addedTime = mQueueItems[0].mTimestamp;

	// Ignore timestamps more than a second in the future
	const bool isPlausible = addedTime < (expectedPresentTime + s2ns(1));
	ALOGW_IF(!isPlausible,
	"[%s] Timestamp %" PRId64 " seems implausible "
	"relative to expectedPresent %" PRId64,
	mName.string(), addedTime, expectedPresentTime);

	const bool isDue = addedTime < expectedPresentTime;
	return isDue \|\| !isPlausible;
	}

	// -----------------------------------------------------------------------
	// Interface implementation for BufferLayer
	// -----------------------------------------------------------------------

	bool BufferQueueLayer::fenceHasSignaled() const {
	if (latchUnsignaledBuffers()) {
	return true;
	}

	if (!hasFrameUpdate()) {
	return true;
	}

	Mutex::Autolock lock(mQueueItemLock);
	if (mQueueItems[0].mIsDroppable) {
	// Even though this buffer's fence may not have signaled yet, it could
	// be replaced by another buffer before it has a chance to, which means
	// that it's possible to get into a situation where a buffer is never
	// able to be latched. To avoid this, grab this buffer anyway.
	return true;
	}
	return mQueueItems[0].mFenceTime->getSignalTime() != Fence::SIGNAL_TIME_PENDING;
	}

	nsecs_t BufferQueueLayer::getDesiredPresentTime() {
	return mConsumer->getTimestamp();
	}

	std::shared_ptr<FenceTime> BufferQueueLayer::getCurrentFenceTime() const {
	return mConsumer->getCurrentFenceTime();
	}

	void BufferQueueLayer::getDrawingTransformMatrix(float *matrix) {
	return mConsumer->getTransformMatrix(matrix);
	}

	// NOTE: SurfaceFlinger's definitions of "Current" and "Drawing" do not neatly map to BufferQueue's
	// These functions get the fields for the frame that is currently in SurfaceFlinger's Drawing state
	// so the functions start with "getDrawing". The data is retrieved from the BufferQueueConsumer's
	// current buffer so the consumer functions start with "getCurrent".
	//
	// This results in the rather confusing functions below.
	uint32_t BufferQueueLayer::getDrawingTransform() const {
	return mConsumer->getCurrentTransform();
	}

	ui::Dataspace BufferQueueLayer::getDrawingDataSpace() const {
	return mConsumer->getCurrentDataSpace();
	}

	Rect BufferQueueLayer::getDrawingCrop() const {
	return mConsumer->getCurrentCrop();
	}

	uint32_t BufferQueueLayer::getDrawingScalingMode() const {
	return mConsumer->getCurrentScalingMode();
	}

	Region BufferQueueLayer::getDrawingSurfaceDamage() const {
	return mConsumer->getSurfaceDamage();
	}

	const HdrMetadata& BufferQueueLayer::getDrawingHdrMetadata() const {
	return mConsumer->getCurrentHdrMetadata();
	}

	int BufferQueueLayer::getDrawingApi() const {
	return mConsumer->getCurrentApi();
	}

	PixelFormat BufferQueueLayer::getPixelFormat() const {
	return mFormat;
	}

	uint64_t BufferQueueLayer::getFrameNumber() const {
	Mutex::Autolock lock(mQueueItemLock);
	return mQueueItems[0].mFrameNumber;
	}

	bool BufferQueueLayer::getAutoRefresh() const {
	return mAutoRefresh;
	}

	bool BufferQueueLayer::getSidebandStreamChanged() const {
	return mSidebandStreamChanged;
	}

	bool BufferQueueLayer::latchSidebandStream(bool& recomputeVisibleRegions) {
	bool sidebandStreamChanged = true;
	if (mSidebandStreamChanged.compare_exchange_strong(sidebandStreamChanged, false)) {
	// mSidebandStreamChanged was changed to false
	auto& layerCompositionState = getCompositionLayer()->editState().frontEnd;
	layerCompositionState.sidebandStream = mConsumer->getSidebandStream();
	if (layerCompositionState.sidebandStream != nullptr) {
	setTransactionFlags(eTransactionNeeded);
	mFlinger->setTransactionFlags(eTraversalNeeded);
	}
	recomputeVisibleRegions = true;

	return true;
	}
	return false;
	}

	bool BufferQueueLayer::hasFrameUpdate() const {
	return mQueuedFrames > 0;
	}

	void BufferQueueLayer::setFilteringEnabled(bool enabled) {
	return mConsumer->setFilteringEnabled(enabled);
	}

	status_t BufferQueueLayer::bindTextureImage() {
	return mConsumer->bindTextureImage();
	}

	status_t BufferQueueLayer::updateTexImage(bool& recomputeVisibleRegions, nsecs_t latchTime) {
	// This boolean is used to make sure that SurfaceFlinger's shadow copy
	// of the buffer queue isn't modified when the buffer queue is returning
	// BufferItem's that weren't actually queued. This can happen in shared
	// buffer mode.
	bool queuedBuffer = false;
	const int32_t layerID = getSequence();
	LayerRejecter r(mDrawingState, getCurrentState(), recomputeVisibleRegions,
	getProducerStickyTransform() != 0, mName.string(), mOverrideScalingMode,
	getTransformToDisplayInverse(), mFreezeGeometryUpdates);

	nsecs_t expectedPresentTime = mFlinger->mScheduler->expectedPresentTime();

	if (isRemovedFromCurrentState()) {
	expectedPresentTime = 0;
	}

	// updateTexImage() below might drop the some buffers at the head of the queue if there is a
	// buffer behind them which is timely to be presented. However this buffer may not be signaled
	// yet. The code below makes sure that this wouldn't happen by setting maxFrameNumber to the
	// last buffer that was signaled.
	uint64_t lastSignaledFrameNumber = mLastFrameNumberReceived;
	{
	Mutex::Autolock lock(mQueueItemLock);
	for (int i = 0; i < mQueueItems.size(); i++) {
	bool fenceSignaled =
	mQueueItems[i].mFenceTime->getSignalTime() != Fence::SIGNAL_TIME_PENDING;
	if (!fenceSignaled) {
	break;
	}
	lastSignaledFrameNumber = mQueueItems[i].mFrameNumber;
	}
	}
	const uint64_t maxFrameNumberToAcquire =
	std::min(mLastFrameNumberReceived.load(), lastSignaledFrameNumber);

	status_t updateResult = mConsumer->updateTexImage(&r, expectedPresentTime, &mAutoRefresh,
	&queuedBuffer, maxFrameNumberToAcquire);
	if (updateResult == BufferQueue::PRESENT_LATER) {
	// Producer doesn't want buffer to be displayed yet. Signal a
	// layer update so we check again at the next opportunity.
	mFlinger->signalLayerUpdate();
	return BAD_VALUE;
	} else if (updateResult == BufferLayerConsumer::BUFFER_REJECTED) {
	// If the buffer has been rejected, remove it from the shadow queue
	// and return early
	if (queuedBuffer) {
	Mutex::Autolock lock(mQueueItemLock);
	mFlinger->mTimeStats->removeTimeRecord(layerID, mQueueItems[0].mFrameNumber);
	mQueueItems.removeAt(0);
	mQueuedFrames--;
	}
	return BAD_VALUE;
	} else if (updateResult != NO_ERROR \|\| mUpdateTexImageFailed) {
	// This can occur if something goes wrong when trying to create the
	// EGLImage for this buffer. If this happens, the buffer has already
	// been released, so we need to clean up the queue and bug out
	// early.
	if (queuedBuffer) {
	Mutex::Autolock lock(mQueueItemLock);
	mQueueItems.clear();
	mQueuedFrames = 0;
	mFlinger->mTimeStats->onDestroy(layerID);
	}

	// Once we have hit this state, the shadow queue may no longer
	// correctly reflect the incoming BufferQueue's contents, so even if
	// updateTexImage starts working, the only safe course of action is
	// to continue to ignore updates.
	mUpdateTexImageFailed = true;

	return BAD_VALUE;
	}

	if (queuedBuffer) {
	// Autolock scope
	auto currentFrameNumber = mConsumer->getFrameNumber();

	Mutex::Autolock lock(mQueueItemLock);

	// Remove any stale buffers that have been dropped during
	// updateTexImage
	while (mQueueItems[0].mFrameNumber != currentFrameNumber) {
	mFlinger->mTimeStats->removeTimeRecord(layerID, mQueueItems[0].mFrameNumber);
	mQueueItems.removeAt(0);
	mQueuedFrames--;
	}

	mFlinger->mTimeStats->setAcquireFence(layerID, currentFrameNumber,
	mQueueItems[0].mFenceTime);
	mFlinger->mTimeStats->setLatchTime(layerID, currentFrameNumber, latchTime);

	mQueueItems.removeAt(0);
	}

	// Decrement the queued-frames count. Signal another event if we
	// have more frames pending.
	if ((queuedBuffer && mQueuedFrames.fetch_sub(1) > 1) \|\| mAutoRefresh) {
	mFlinger->signalLayerUpdate();
	}

	return NO_ERROR;
	}

	status_t BufferQueueLayer::updateActiveBuffer() {
	// update the active buffer
	mActiveBuffer = mConsumer->getCurrentBuffer(&mActiveBufferSlot, &mActiveBufferFence);
	auto& layerCompositionState = getCompositionLayer()->editState().frontEnd;
	layerCompositionState.buffer = mActiveBuffer;
	layerCompositionState.bufferSlot = mActiveBufferSlot;

	if (mActiveBuffer == nullptr) {
	// this can only happen if the very first buffer was rejected.
	return BAD_VALUE;
	}
	return NO_ERROR;
	}

	status_t BufferQueueLayer::updateFrameNumber(nsecs_t latchTime) {
	mPreviousFrameNumber = mCurrentFrameNumber;
	mCurrentFrameNumber = mConsumer->getFrameNumber();

	{
	Mutex::Autolock lock(mFrameEventHistoryMutex);
	mFrameEventHistory.addLatch(mCurrentFrameNumber, latchTime);
	}
	return NO_ERROR;
	}

	void BufferQueueLayer::setHwcLayerBuffer(const sp<const DisplayDevice>& display) {
	const auto outputLayer = findOutputLayerForDisplay(display);
	LOG_FATAL_IF(!outputLayer);
	LOG_FATAL_IF(!outputLayer->getState.hwc);
	auto& hwcLayer = (*outputLayer->getState().hwc).hwcLayer;

	uint32_t hwcSlot = 0;
	sp<GraphicBuffer> hwcBuffer;

	// INVALID_BUFFER_SLOT is used to identify BufferStateLayers. Default to 0
	// for BufferQueueLayers
	int slot = (mActiveBufferSlot == BufferQueue::INVALID_BUFFER_SLOT) ? 0 : mActiveBufferSlot;
	(*outputLayer->editState().hwc)
	.hwcBufferCache.getHwcBuffer(slot, mActiveBuffer, &hwcSlot, &hwcBuffer);

	auto acquireFence = mConsumer->getCurrentFence();
	auto error = hwcLayer->setBuffer(hwcSlot, hwcBuffer, acquireFence);
	if (error != HWC2::Error::None) {
	ALOGE("[%s] Failed to set buffer %p: %s (%d)", mName.string(), mActiveBuffer->handle,
	to_string(error).c_str(), static_cast<int32_t>(error));
	}

	auto& layerCompositionState = getCompositionLayer()->editState().frontEnd;
	layerCompositionState.bufferSlot = mActiveBufferSlot;
	layerCompositionState.buffer = mActiveBuffer;
	layerCompositionState.acquireFence = acquireFence;
	}

	// -----------------------------------------------------------------------
	// Interface implementation for BufferLayerConsumer::ContentsChangedListener
	// -----------------------------------------------------------------------

	void BufferQueueLayer::fakeVsync() {
	mRefreshPending = false;
	bool ignored = false;
	latchBuffer(ignored, systemTime());
	usleep(16000);
	releasePendingBuffer(systemTime());
	}

	void BufferQueueLayer::onFrameAvailable(const BufferItem& item) {
	// Add this buffer from our internal queue tracker
	{ // Autolock scope
	if (mFlinger->mUseSmart90ForVideo) {
	// Report mApi ID for each layer.
	mFlinger->mScheduler->addNativeWindowApi(item.mApi);
	}

	Mutex::Autolock lock(mQueueItemLock);
	// Reset the frame number tracker when we receive the first buffer after
	// a frame number reset
	if (item.mFrameNumber == 1) {
	mLastFrameNumberReceived = 0;
	}

	// Ensure that callbacks are handled in order
	while (item.mFrameNumber != mLastFrameNumberReceived + 1) {
	status_t result = mQueueItemCondition.waitRelative(mQueueItemLock, ms2ns(500));
	if (result != NO_ERROR) {
	ALOGE("[%s] Timed out waiting on callback", mName.string());
	}
	}

	mQueueItems.push_back(item);
	mQueuedFrames++;

	// Wake up any pending callbacks
	mLastFrameNumberReceived = item.mFrameNumber;
	mQueueItemCondition.broadcast();
	}

	mFlinger->mInterceptor->saveBufferUpdate(this, item.mGraphicBuffer->getWidth(),
	item.mGraphicBuffer->getHeight(), item.mFrameNumber);

	// If this layer is orphaned, then we run a fake vsync pulse so that
	// dequeueBuffer doesn't block indefinitely.
	if (isRemovedFromCurrentState()) {
	fakeVsync();
	} else {
	mFlinger->signalLayerUpdate();
	}
	}

	void BufferQueueLayer::onFrameReplaced(const BufferItem& item) {
	{ // Autolock scope
	Mutex::Autolock lock(mQueueItemLock);

	// Ensure that callbacks are handled in order
	while (item.mFrameNumber != mLastFrameNumberReceived + 1) {
	status_t result = mQueueItemCondition.waitRelative(mQueueItemLock, ms2ns(500));
	if (result != NO_ERROR) {
	ALOGE("[%s] Timed out waiting on callback", mName.string());
	}
	}

	if (!hasFrameUpdate()) {
	ALOGE("Can't replace a frame on an empty queue");
	return;
	}
	mQueueItems.editItemAt(mQueueItems.size() - 1) = item;

	// Wake up any pending callbacks
	mLastFrameNumberReceived = item.mFrameNumber;
	mQueueItemCondition.broadcast();
	}
	}

	void BufferQueueLayer::onSidebandStreamChanged() {
	bool sidebandStreamChanged = false;
	if (mSidebandStreamChanged.compare_exchange_strong(sidebandStreamChanged, true)) {
	// mSidebandStreamChanged was changed to true
	mFlinger->signalLayerUpdate();
	}
	}

	// -----------------------------------------------------------------------

	void BufferQueueLayer::onFirstRef() {
	BufferLayer::onFirstRef();

	// Creates a custom BufferQueue for SurfaceFlingerConsumer to use
	sp<IGraphicBufferProducer> producer;
	sp<IGraphicBufferConsumer> consumer;
	BufferQueue::createBufferQueue(&producer, &consumer, true);
	mProducer = new MonitoredProducer(producer, mFlinger, this);
	{
	// Grab the SF state lock during this since it's the only safe way to access RenderEngine
	Mutex::Autolock lock(mFlinger->mStateLock);
	mConsumer =
	new BufferLayerConsumer(consumer, mFlinger->getRenderEngine(), mTextureName, this);
	}
	mConsumer->setConsumerUsageBits(getEffectiveUsage(0));
	mConsumer->setContentsChangedListener(this);
	mConsumer->setName(mName);

	// BufferQueueCore::mMaxDequeuedBufferCount is default to 1
	if (!mFlinger->isLayerTripleBufferingDisabled()) {
	mProducer->setMaxDequeuedBufferCount(2);
	}

	if (const auto display = mFlinger->getDefaultDisplayDevice()) {
	updateTransformHint(display);
	}
	}

	status_t BufferQueueLayer::setDefaultBufferProperties(uint32_t w, uint32_t h, PixelFormat format) {
	uint32_t const maxSurfaceDims =
	std::min(mFlinger->getMaxTextureSize(), mFlinger->getMaxViewportDims());

	// never allow a surface larger than what our underlying GL implementation
	// can handle.
	if ((uint32_t(w) > maxSurfaceDims) \|\| (uint32_t(h) > maxSurfaceDims)) {
	ALOGE("dimensions too large %u x %u", uint32_t(w), uint32_t(h));
	return BAD_VALUE;
	}

	mFormat = format;

	setDefaultBufferSize(w, h);
	mConsumer->setDefaultBufferFormat(format);
	mConsumer->setConsumerUsageBits(getEffectiveUsage(0));

	return NO_ERROR;
	}

	sp<IGraphicBufferProducer> BufferQueueLayer::getProducer() const {
	return mProducer;
	}

	uint32_t BufferQueueLayer::getProducerStickyTransform() const {
	int producerStickyTransform = 0;
	int ret = mProducer->query(NATIVE_WINDOW_STICKY_TRANSFORM, &producerStickyTransform);
	if (ret != OK) {
	ALOGW("%s: Error %s (%d) while querying window sticky transform.", __FUNCTION__,
	strerror(-ret), ret);
	return 0;
	}
	return static_cast<uint32_t>(producerStickyTransform);
	}

	} // namespace android