[Feat] (MG_Backend/DirectVulkan): implement naive transient/resident buffer, and heuristics to downgrade resident buffer to transient

MobileGL/MG_Backend/DirectVulkan/Renderer/VkBufferManager.cpp

@@ -9,6 +9,12 @@
 #include "VkBufferManager.h"
 
 namespace MobileGL::MG_Backend::DirectVulkan {
+    namespace {
+        constexpr Uint32 kResidentBufferGCInterval = 60;
+        constexpr VmaAllocationCreateFlags kResidentBufferAllocationFlags =
+            VMA_ALLOCATION_CREATE_HOST_ACCESS_SEQUENTIAL_WRITE_BIT;
+    } // namespace
+
     Bool VkBufferManager::Initialize(const VkBufferManagerInitInfo& initInfo) {
         Shutdown();
 
@@ -16,12 +22,18 @@ namespace MobileGL::MG_Backend::DirectVulkan {
         MOBILEGL_ASSERT(initInfo.frameCount > 0, "VkBufferManager::Initialize requires non-zero frame count");
 
         m_initInfo = initInfo;
+        m_deferredResidentReleases.resize(initInfo.frameCount);
+        m_currentFrameIndex = 0;
         return InitializeTransientArenas();
     }
 
     void VkBufferManager::Shutdown() {
         m_transientUploadArena.Shutdown();
+        DestroyResidentBuffers();
+        DestroyDeferredResidentReleases();
         m_initInfo = {};
+        m_currentFrameIndex = 0;
+        m_residentGcTick = 0;
     }
 
     Bool VkBufferManager::RecreateTransientArenas(Uint32 frameCount) {
@@ -30,14 +42,21 @@ namespace MobileGL::MG_Backend::DirectVulkan {
 
         m_transientUploadArena.Shutdown();
         m_initInfo.frameCount = frameCount;
+        DestroyDeferredResidentReleases();
+        m_deferredResidentReleases.resize(frameCount);
+        m_currentFrameIndex = 0;
         return InitializeTransientArenas();
     }
 
     void VkBufferManager::BeginFrame(Uint32 frameIndex) {
+        MOBILEGL_ASSERT(frameIndex < m_deferredResidentReleases.size(),
+                        "VkBufferManager::BeginFrame frame index out of range");
+        m_currentFrameIndex = frameIndex;
+        CollectDeferredResidentReleases(frameIndex);
         m_transientUploadArena.BeginFrame(frameIndex);
     }
 
-    Bool VkBufferManager::UploadTransient(TransientBufferKind kind, Uint32 frameIndex, const void* data,
+    Bool VkBufferManager::UploadTransient(BufferKind kind, Uint32 frameIndex, const void* data,
                                           VkDeviceSize size, VkDeviceSize alignment, BufferSlice& outSlice) {
         (void)kind;
         return m_transientUploadArena.Upload(frameIndex, data, size, alignment, outSlice);
@@ -55,4 +74,173 @@ namespace MobileGL::MG_Backend::DirectVulkan {
             .persistentlyMapped = m_initInfo.transientPersistentMapping,
         });
     }
+
+    Bool VkBufferManager::SyncResidentBuffer(BufferKind kind,
+                                             const SharedPtr<MG_State::GLState::BufferObject>& bufferObject,
+                                             BufferSlice& outSlice) {
+        const VkBufferUsageFlags requiredUsage = GetVkBufferUsage(kind);
+        MOBILEGL_ASSERT(requiredUsage != 0,
+                        "VkBufferManager::SyncResidentBuffer only supports resident vertex/index buffers");
+        MOBILEGL_ASSERT(bufferObject != nullptr, "VkBufferManager::SyncResidentBuffer requires valid buffer object");
+        CollectResidentGarbageIfNeeded();
+
+        const auto* bufferData = bufferObject->GetDataReadOnly().get();
+        MOBILEGL_ASSERT(bufferData != nullptr, "VkBufferManager::SyncResidentBuffer requires frontend buffer data");
+
+        const VkDeviceSize bufferSize = static_cast<VkDeviceSize>(bufferObject->GetSize());
+        if (bufferSize == 0) {
+            MGLOG_E("VkBufferManager::SyncResidentBuffer failed: buffer size is zero");
+            return false;
+        }
+
+        auto& entry = m_residentBuffers[bufferObject.get()];
+        entry.aliveRef = bufferObject;
+
+        const auto changeBits = bufferObject->GetChangeBits();
+        const Bool needsRecreate = !entry.buffer.IsValid() || entry.size != bufferSize ||
+                                   ((entry.usage & requiredUsage) != requiredUsage) ||
+                                   (changeBits & BufferChangeBits::PreferReallocationBit);
+        if (needsRecreate) {
+            const VkBufferUsageFlags recreatedUsage = entry.usage | requiredUsage;
+            DeferResidentRelease(std::move(entry.buffer));
+            const Bool created = entry.buffer.Create({
+                .allocator = m_initInfo.allocator,
+                .size = bufferSize,
+                .usage = recreatedUsage,
+                .memoryUsage = VMA_MEMORY_USAGE_AUTO,
+                .allocationFlags = kResidentBufferAllocationFlags,
+            });
+            if (!created || entry.buffer.Map() == nullptr) {
+                MGLOG_E("VkBufferManager::SyncResidentBuffer failed: unable to create resident buffer");
+                entry.buffer.Destroy();
+                entry.size = 0;
+                entry.usage = 0;
+                return false;
+            }
+            if (!entry.buffer.Upload(bufferData->data(), bufferSize, 0)) {
+                MGLOG_E("VkBufferManager::SyncResidentBuffer failed: initial upload failed");
+                entry.buffer.Destroy();
+                entry.size = 0;
+                entry.usage = 0;
+                return false;
+            }
+            entry.size = bufferSize;
+            entry.usage = recreatedUsage;
+            bufferObject->ClearDirty();
+            outSlice = entry.buffer.GetSlice(0, bufferSize);
+            return true;
+        }
+
+        if (changeBits & BufferChangeBits::DirtyBit) {
+            const auto& dirtyRanges = bufferObject->GetDirtyRanges();
+            for (const auto& range : dirtyRanges) {
+                const VkDeviceSize rangeOffset = static_cast<VkDeviceSize>(range.start);
+                const VkDeviceSize rangeSize = static_cast<VkDeviceSize>(range.end - range.start);
+                if (rangeSize == 0) {
+                    continue;
+                }
+                if (!entry.buffer.Upload(bufferData->data() + range.start, rangeSize, rangeOffset)) {
+                    MGLOG_E("VkBufferManager::SyncResidentBuffer failed: dirty range upload failed");
+                    return false;
+                }
+            }
+            bufferObject->ClearDirty();
+        }
+
+        outSlice = entry.buffer.GetSlice(0, bufferSize);
+        return true;
+    }
+
+    void VkBufferManager::DowngradeResidentBufferToTransient(const SharedPtr<MG_State::GLState::BufferObject>& bufferObject) {
+        if (bufferObject == nullptr) {
+            return;
+        }
+
+        auto it = m_residentBuffers.find(bufferObject.get());
+        if (it == m_residentBuffers.end()) {
+            return;
+        }
+
+        DeferResidentRelease(std::move(it->second.buffer));
+        m_residentBuffers.erase(it);
+    }
+
+    void VkBufferManager::DeferResidentRelease(VkBufferObject&& buffer) {
+        if (!buffer.IsValid()) {
+            return;
+        }
+
+        if (m_deferredResidentReleases.empty()) {
+            buffer.Destroy();
+            return;
+        }
+
+        MOBILEGL_ASSERT(m_currentFrameIndex < m_deferredResidentReleases.size(),
+                        "VkBufferManager::DeferResidentRelease current frame index out of range");
+        m_deferredResidentReleases[m_currentFrameIndex].push_back(std::move(buffer));
+    }
+
+    void VkBufferManager::CollectDeferredResidentReleases(Uint32 frameIndex) {
+        MOBILEGL_ASSERT(frameIndex < m_deferredResidentReleases.size(),
+                        "VkBufferManager::CollectDeferredResidentReleases frame index out of range");
+        m_deferredResidentReleases[frameIndex].clear();
+    }
+
+    VkBufferUsageFlags VkBufferManager::GetVkBufferUsage(BufferKind kind) {
+        switch (kind) {
+        case BufferKind::Vertex:
+        case BufferKind::Index:
+            // A GL buffer can be rebound between ARRAY_BUFFER and ELEMENT_ARRAY_BUFFER,
+            // and may even be used as both within the same draw setup. Keep resident
+            // vertex/index buffers compatible with both roles from the start so we
+            // never need to recreate a buffer after it has already been bound.
+            return VK_BUFFER_USAGE_VERTEX_BUFFER_BIT | VK_BUFFER_USAGE_INDEX_BUFFER_BIT;
+        case BufferKind::Uniform:
+        default:
+            return 0;
+        }
+    }
+
+    void VkBufferManager::CollectResidentGarbageIfNeeded() {
+        ++m_residentGcTick;
+        if (m_residentGcTick < kResidentBufferGCInterval) {
+            return;
+        }
+        CollectResidentGarbageNow();
+        m_residentGcTick = 0;
+    }
+
+    void VkBufferManager::CollectResidentGarbageNow() {
+        Vector<MG_State::GLState::BufferObject*> staleBuffers;
+        staleBuffers.reserve(m_residentBuffers.size());
+
+        for (const auto& [rawBuffer, entry] : m_residentBuffers) {
+            if (entry.aliveRef.expired()) {
+                staleBuffers.push_back(rawBuffer);
+            }
+        }
+
+        for (const auto* rawBuffer : staleBuffers) {
+            auto it = m_residentBuffers.find(const_cast<MG_State::GLState::BufferObject*>(rawBuffer));
+            if (it == m_residentBuffers.end()) {
+                continue;
+            }
+            DeferResidentRelease(std::move(it->second.buffer));
+            m_residentBuffers.erase(it);
+        }
+    }
+
+    void VkBufferManager::DestroyDeferredResidentReleases() {
+        for (auto& deferredReleases : m_deferredResidentReleases) {
+            deferredReleases.clear();
+        }
+        m_deferredResidentReleases.clear();
+    }
+
+    void VkBufferManager::DestroyResidentBuffers() {
+        for (auto& [_, entry] : m_residentBuffers) {
+            entry.buffer.Destroy();
+        }
+        m_residentBuffers.clear();
+    }
 } // namespace MobileGL::MG_Backend::DirectVulkan