Push HWC cache slot generation down into CompositionEngine
Stop caching buffers inside SurfaceFlinger and remove the tight coupling
between SurfaceFlinger's ClientCache and the Hardware Composer cache.
This allows a better seperation of responsibility, where buffer cache
management is not split between HwcSlotGenerator and HwcBufferCache, but
is instead solely handled by HwcBufferCache.
Note that FramebufferSurface and VirtualDisplaySurface no longer use
HwcBufferCache, but instead use their own cache slot management that
is solely based on BufferQueue slot numbers.
Also do minor refactoring in FramebufferSurface to simplify code.
Bug: 258196272
Test: started and stopped multiple YouTube videos on adt4 and verified
no change in graphic buffer usage
Test: atest HwcBufferCacheTest
Test: atest OutputPrepareTest
Change-Id: Ica7955ab4bc70e3c70207390e36dff73a2fc4949
diff --git a/services/surfaceflinger/CompositionEngine/src/HwcBufferCache.cpp b/services/surfaceflinger/CompositionEngine/src/HwcBufferCache.cpp
index f95382d..d64fd57 100644
--- a/services/surfaceflinger/CompositionEngine/src/HwcBufferCache.cpp
+++ b/services/surfaceflinger/CompositionEngine/src/HwcBufferCache.cpp
@@ -16,43 +16,80 @@
#include <compositionengine/impl/HwcBufferCache.h>
-// TODO(b/129481165): remove the #pragma below and fix conversion issues
-#pragma clang diagnostic push
-#pragma clang diagnostic ignored "-Wconversion"
-
#include <gui/BufferQueue.h>
#include <ui/GraphicBuffer.h>
-// TODO(b/129481165): remove the #pragma below and fix conversion issues
-#pragma clang diagnostic pop // ignored "-Wconversion"
-
namespace android::compositionengine::impl {
HwcBufferCache::HwcBufferCache() {
- std::fill(std::begin(mBuffers), std::end(mBuffers), wp<GraphicBuffer>(nullptr));
+ for (uint32_t i = 0; i < kMaxLayerBufferCount; i++) {
+ mFreeSlots.push(i);
+ }
}
-void HwcBufferCache::getHwcBuffer(int slot, const sp<GraphicBuffer>& buffer, uint32_t* outSlot,
- sp<GraphicBuffer>* outBuffer) {
- // default is 0
- if (slot == BufferQueue::INVALID_BUFFER_SLOT || slot < 0 ||
- slot >= static_cast<int32_t>(kMaxLayerBufferCount)) {
- *outSlot = 0;
- } else {
- *outSlot = static_cast<uint32_t>(slot);
+HwcSlotAndBuffer HwcBufferCache::getHwcSlotAndBuffer(const sp<GraphicBuffer>& buffer) {
+ // TODO(b/261930578): This is for unit tests which don't mock GraphicBuffers but instead send
+ // in nullptrs.
+ if (buffer == nullptr) {
+ return {0, nullptr};
}
-
- auto& currentBuffer = mBuffers[*outSlot];
- wp<GraphicBuffer> weakCopy(buffer);
- if (currentBuffer == weakCopy) {
- // already cached in HWC, skip sending the buffer
- *outBuffer = nullptr;
- } else {
- *outBuffer = buffer;
-
- // update cache
- currentBuffer = buffer;
+ if (auto i = mCacheByBufferId.find(buffer->getId()); i != mCacheByBufferId.end()) {
+ Cache& cache = i->second;
+ // mark this cache slot as more recently used so it won't get evicted anytime soon
+ cache.lruCounter = mLeastRecentlyUsedCounter++;
+ return {cache.slot, nullptr};
}
+ return {cache(buffer), buffer};
+}
+
+HwcSlotAndBuffer HwcBufferCache::getHwcSlotAndBufferForOverride(const sp<GraphicBuffer>& buffer) {
+ if (buffer == mLastOverrideBuffer) {
+ return {kOverrideBufferSlot, nullptr};
+ }
+ mLastOverrideBuffer = buffer;
+ return {kOverrideBufferSlot, buffer};
+}
+
+uint32_t HwcBufferCache::uncache(uint64_t bufferId) {
+ if (auto i = mCacheByBufferId.find(bufferId); i != mCacheByBufferId.end()) {
+ uint32_t slot = i->second.slot;
+ mCacheByBufferId.erase(i);
+ mFreeSlots.push(slot);
+ return slot;
+ }
+ if (mLastOverrideBuffer && bufferId == mLastOverrideBuffer->getId()) {
+ mLastOverrideBuffer = nullptr;
+ return kOverrideBufferSlot;
+ }
+ return UINT32_MAX;
+}
+
+uint32_t HwcBufferCache::cache(const sp<GraphicBuffer>& buffer) {
+ Cache cache;
+ cache.slot = getLeastRecentlyUsedSlot();
+ cache.lruCounter = mLeastRecentlyUsedCounter++;
+ cache.buffer = buffer;
+ mCacheByBufferId.emplace(buffer->getId(), cache);
+ return cache.slot;
+}
+
+uint32_t HwcBufferCache::getLeastRecentlyUsedSlot() {
+ if (mFreeSlots.empty()) {
+ assert(!mCacheByBufferId.empty());
+ // evict the least recently used cache entry
+ auto cacheToErase = mCacheByBufferId.begin();
+ for (auto i = cacheToErase; i != mCacheByBufferId.end(); ++i) {
+ if (i->second.lruCounter < cacheToErase->second.lruCounter) {
+ cacheToErase = i;
+ }
+ }
+ uint32_t slot = cacheToErase->second.slot;
+ mCacheByBufferId.erase(cacheToErase);
+ mFreeSlots.push(slot);
+ }
+ uint32_t slot = mFreeSlots.top();
+ mFreeSlots.pop();
+ return slot;
}
} // namespace android::compositionengine::impl