uint32_t hwcSlot = 0;
sp<GraphicBuffer> hwcBuffer;
(*outputLayer->editState().hwc)
- .hwcBufferCache.getHwcBuffer(mActiveBufferSlot, mActiveBuffer, &hwcSlot, &hwcBuffer);
+ .hwcBufferCache.getHwcBuffer(mActiveBuffer, &hwcSlot, &hwcBuffer);
auto acquireFence = mConsumer->getCurrentFence();
auto error = hwcLayer->setBuffer(hwcSlot, hwcBuffer, acquireFence);
void BufferStateLayer::setHwcLayerBuffer(const sp<const DisplayDevice>& display) {
const auto outputLayer = findOutputLayerForDisplay(display);
LOG_FATAL_IF(!outputLayer || !outputLayer->getState().hwc);
- auto& hwcLayer = (*outputLayer->getState().hwc).hwcLayer;
+ auto& hwcInfo = *outputLayer->editState().hwc;
+ auto& hwcLayer = hwcInfo.hwcLayer;
const State& s(getDrawingState());
- // TODO(marissaw): support more than one slot
+ // obtain slot
uint32_t hwcSlot = 0;
+ sp<GraphicBuffer> buffer;
+ hwcInfo.hwcBufferCache.getHwcBuffer(s.buffer, &hwcSlot, &buffer);
- auto error = hwcLayer->setBuffer(hwcSlot, s.buffer, s.acquireFence);
+ auto error = hwcLayer->setBuffer(hwcSlot, buffer, s.acquireFence);
if (error != HWC2::Error::None) {
ALOGE("[%s] Failed to set buffer %p: %s (%d)", mName.string(),
s.buffer->handle, to_string(error).c_str(), static_cast<int32_t>(error));
#include <cstdint>
#include <vector>
+#include <gui/BufferQueue.h>
#include <utils/StrongPointer.h>
namespace android {
class HwcBufferCache {
public:
HwcBufferCache();
-
- // Given a buffer queue slot and buffer, return the HWC cache slot and
+ // Given a buffer, return the HWC cache slot and
// buffer to be sent to HWC.
//
// outBuffer is set to buffer when buffer is not in the HWC cache;
// otherwise, outBuffer is set to nullptr.
- void getHwcBuffer(int slot, const sp<GraphicBuffer>& buffer, uint32_t* outSlot,
+ void getHwcBuffer(const sp<GraphicBuffer>& buffer, uint32_t* outSlot,
sp<GraphicBuffer>* outBuffer);
+protected:
+ int getSlot(const sp<GraphicBuffer>& buffer);
+ int getLeastRecentlyUsedSlot();
+ uint64_t getCounter();
+
private:
- // a vector as we expect "slot" to be in the range of [0, 63] (that is,
- // less than BufferQueue::NUM_BUFFER_SLOTS).
- std::vector<sp<GraphicBuffer>> mBuffers;
+ // an array where the index corresponds to a slot and the value corresponds to a (counter,
+ // buffer) pair. "counter" is a unique value that indicates the last time this slot was updated
+ // or used and allows us to keep track of the least-recently used buffer.
+ std::pair<uint64_t, wp<GraphicBuffer>> mBuffers[BufferQueue::NUM_BUFFER_SLOTS];
+
+ // The cache increments this counter value when a slot is updated or used.
+ // Used to track the least recently-used buffer
+ uint64_t mCounter = 1;
};
} // namespace compositionengine::impl
namespace android::compositionengine::impl {
HwcBufferCache::HwcBufferCache() {
- mBuffers.reserve(BufferQueue::NUM_BUFFER_SLOTS);
+ std::fill(std::begin(mBuffers), std::end(mBuffers),
+ std::pair<uint64_t, wp<GraphicBuffer>>(0, nullptr));
}
-
-void HwcBufferCache::getHwcBuffer(int slot, const sp<GraphicBuffer>& buffer, uint32_t* outSlot,
- sp<GraphicBuffer>* outBuffer) {
- if (slot == BufferQueue::INVALID_BUFFER_SLOT || slot < 0) {
- // default to slot 0
- slot = 0;
+int HwcBufferCache::getSlot(const sp<GraphicBuffer>& buffer) {
+ // search for cached buffer first
+ for (int i = 0; i < BufferQueue::NUM_BUFFER_SLOTS; i++) {
+ if (mBuffers[i].second == buffer) {
+ return i;
+ }
}
- if (static_cast<size_t>(slot) >= mBuffers.size()) {
- mBuffers.resize(slot + 1);
- }
+ // use the least-recently used slot
+ return getLeastRecentlyUsedSlot();
+}
- *outSlot = slot;
+int HwcBufferCache::getLeastRecentlyUsedSlot() {
+ auto iter = std::min_element(std::begin(mBuffers), std::end(mBuffers));
+ return std::distance(std::begin(mBuffers), iter);
+}
+
+void HwcBufferCache::getHwcBuffer(const sp<GraphicBuffer>& buffer, uint32_t* outSlot,
+ sp<GraphicBuffer>* outBuffer) {
+ *outSlot = getSlot(buffer);
- if (mBuffers[slot] == buffer) {
+ auto& [currentCounter, currentBuffer] = mBuffers[*outSlot];
+ if (currentBuffer == buffer) {
// already cached in HWC, skip sending the buffer
*outBuffer = nullptr;
+ currentCounter = getCounter();
} else {
*outBuffer = buffer;
// update cache
- mBuffers[slot] = buffer;
+ currentBuffer = buffer;
+ currentCounter = getCounter();
}
}
+uint64_t HwcBufferCache::getCounter() {
+ return mCounter++;
+}
} // namespace android::compositionengine::impl
namespace android::compositionengine {
namespace {
+class TestableHwcBufferCache : public impl::HwcBufferCache {
+public:
+ void getHwcBuffer(const sp<GraphicBuffer>& buffer, uint32_t* outSlot,
+ sp<GraphicBuffer>* outBuffer) {
+ HwcBufferCache::getHwcBuffer(buffer, outSlot, outBuffer);
+ }
+ int getSlot(const sp<GraphicBuffer>& buffer) { return HwcBufferCache::getSlot(buffer); }
+ int getLeastRecentlyUsedSlot() { return HwcBufferCache::getLeastRecentlyUsedSlot(); }
+};
+
class HwcBufferCacheTest : public testing::Test {
public:
~HwcBufferCacheTest() override = default;
- void testSlot(const int inSlot, const uint32_t expectedSlot) {
- uint32_t outSlot;
- sp<GraphicBuffer> outBuffer;
-
- // The first time, the output is the same as the input
- mCache.getHwcBuffer(inSlot, mBuffer1, &outSlot, &outBuffer);
- EXPECT_EQ(expectedSlot, outSlot);
- EXPECT_EQ(mBuffer1, outBuffer);
-
- // The second time with the same buffer, the outBuffer is nullptr.
- mCache.getHwcBuffer(inSlot, mBuffer1, &outSlot, &outBuffer);
- EXPECT_EQ(expectedSlot, outSlot);
- EXPECT_EQ(nullptr, outBuffer.get());
-
- // With a new buffer, the outBuffer is the input.
- mCache.getHwcBuffer(inSlot, mBuffer2, &outSlot, &outBuffer);
- EXPECT_EQ(expectedSlot, outSlot);
- EXPECT_EQ(mBuffer2, outBuffer);
-
- // Again, the second request with the same buffer sets outBuffer to nullptr.
- mCache.getHwcBuffer(inSlot, mBuffer2, &outSlot, &outBuffer);
- EXPECT_EQ(expectedSlot, outSlot);
- EXPECT_EQ(nullptr, outBuffer.get());
-
- // Setting a slot to use nullptr lookslike works, but note that
- // the output values make it look like no new buffer is being set....
- mCache.getHwcBuffer(inSlot, sp<GraphicBuffer>(), &outSlot, &outBuffer);
- EXPECT_EQ(expectedSlot, outSlot);
- EXPECT_EQ(nullptr, outBuffer.get());
- }
-
- impl::HwcBufferCache mCache;
+ TestableHwcBufferCache mCache;
sp<GraphicBuffer> mBuffer1{new GraphicBuffer(1, 1, HAL_PIXEL_FORMAT_RGBA_8888, 1, 0)};
sp<GraphicBuffer> mBuffer2{new GraphicBuffer(1, 1, HAL_PIXEL_FORMAT_RGBA_8888, 1, 0)};
};
-TEST_F(HwcBufferCacheTest, cacheWorksForSlotZero) {
- testSlot(0, 0);
-}
+TEST_F(HwcBufferCacheTest, testSlot) {
+ uint32_t outSlot;
+ sp<GraphicBuffer> outBuffer;
-TEST_F(HwcBufferCacheTest, cacheWorksForMaxSlot) {
- testSlot(BufferQueue::NUM_BUFFER_SLOTS - 1, BufferQueue::NUM_BUFFER_SLOTS - 1);
-}
+ // The first time, the output is the same as the input
+ mCache.getHwcBuffer(mBuffer1, &outSlot, &outBuffer);
+ EXPECT_EQ(0, outSlot);
+ EXPECT_EQ(mBuffer1, outBuffer);
-TEST_F(HwcBufferCacheTest, cacheMapsNegativeSlotToZero) {
- testSlot(-123, 0);
+ // The second time with the same buffer, the outBuffer is nullptr.
+ mCache.getHwcBuffer(mBuffer1, &outSlot, &outBuffer);
+ EXPECT_EQ(0, outSlot);
+ EXPECT_EQ(nullptr, outBuffer.get());
+
+ // With a new buffer, the outBuffer is the input.
+ mCache.getHwcBuffer(mBuffer2, &outSlot, &outBuffer);
+ EXPECT_EQ(1, outSlot);
+ EXPECT_EQ(mBuffer2, outBuffer);
+
+ // Again, the second request with the same buffer sets outBuffer to nullptr.
+ mCache.getHwcBuffer(mBuffer2, &outSlot, &outBuffer);
+ EXPECT_EQ(1, outSlot);
+ EXPECT_EQ(nullptr, outBuffer.get());
+
+ // Setting a slot to use nullptr lookslike works, but note that
+ // the output values make it look like no new buffer is being set....
+ mCache.getHwcBuffer(sp<GraphicBuffer>(), &outSlot, &outBuffer);
+ EXPECT_EQ(2, outSlot);
+ EXPECT_EQ(nullptr, outBuffer.get());
}
-TEST_F(HwcBufferCacheTest, cacheMapsInvalidBufferSlotToZero) {
- testSlot(BufferQueue::INVALID_BUFFER_SLOT, 0);
+TEST_F(HwcBufferCacheTest, testGetLeastRecentlyUsedSlot) {
+ int slot;
+ uint32_t outSlot;
+ sp<GraphicBuffer> outBuffer;
+
+ // fill up cache
+ for (int i = 0; i < BufferQueue::NUM_BUFFER_SLOTS; i++) {
+ sp<GraphicBuffer> buf{new GraphicBuffer(1, 1, HAL_PIXEL_FORMAT_RGBA_8888, 1, 0)};
+ mCache.getHwcBuffer(buf, &outSlot, &outBuffer);
+ EXPECT_EQ(buf, outBuffer);
+ EXPECT_EQ(i, outSlot);
+ }
+
+ slot = mCache.getLeastRecentlyUsedSlot();
+ EXPECT_EQ(0, slot);
+
+ mCache.getHwcBuffer(mBuffer1, &outSlot, &outBuffer);
+ EXPECT_EQ(0, outSlot);
+ EXPECT_EQ(mBuffer1, outBuffer);
+
+ slot = mCache.getLeastRecentlyUsedSlot();
+ EXPECT_EQ(1, slot);
}
} // namespace
BufferItem item;
status_t err = acquireBufferLocked(&item, 0);
if (err == BufferQueue::NO_BUFFER_AVAILABLE) {
- mHwcBufferCache.getHwcBuffer(mCurrentBufferSlot, mCurrentBuffer,
- &outSlot, &outBuffer);
+ mHwcBufferCache.getHwcBuffer(mCurrentBuffer, &outSlot, &outBuffer);
return NO_ERROR;
} else if (err != NO_ERROR) {
ALOGE("error acquiring buffer: %s (%d)", strerror(-err), err);
mCurrentFence = item.mFence;
outFence = item.mFence;
- mHwcBufferCache.getHwcBuffer(mCurrentBufferSlot, mCurrentBuffer,
- &outSlot, &outBuffer);
+ mHwcBufferCache.getHwcBuffer(mCurrentBuffer, &outSlot, &outBuffer);
outDataspace = static_cast<Dataspace>(item.mDataSpace);
status_t result = mHwc.setClientTarget(mDisplayId, outSlot, outFence, outBuffer, outDataspace);
if (result != NO_ERROR) {
if (fbBuffer != nullptr) {
uint32_t hwcSlot = 0;
sp<GraphicBuffer> hwcBuffer;
- mHwcBufferCache.getHwcBuffer(mFbProducerSlot, fbBuffer,
- &hwcSlot, &hwcBuffer);
+ mHwcBufferCache.getHwcBuffer(fbBuffer, &hwcSlot, &hwcBuffer);
// TODO: Correctly propagate the dataspace from GL composition
result = mHwc.setClientTarget(*mDisplayId, hwcSlot, mFbFence, hwcBuffer,
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