pine/app/src/main/cpp/skyline/gpu/presentation_engine.cpp

// SPDX-License-Identifier: MPL-2.0
// Copyright © 2020 Skyline Team and Contributors (https://github.com/skyline-emu/)

#include <android/native_window_jni.h>
#include <android/choreographer.h>
#include <common/settings.h>
#include <common/signal.h>
#include <jvm.h>
#include <gpu.h>
#include <loader/loader.h>
#include <kernel/types/KProcess.h>
#include "presentation_engine.h"
#include "native_window.h"
#include "texture/format.h"

extern jint Fps;
extern jfloat AverageFrametimeMs;
extern jfloat AverageFrametimeDeviationMs;

namespace skyline::gpu {
    using namespace service::hosbinder;

    PresentationEngine::PresentationEngine(const DeviceState &state, GPU &gpu)
        : state(state),
          gpu(gpu),
          acquireFence(gpu.vkDevice, vk::FenceCreateInfo{}),
          presentationTrack(static_cast<u64>(trace::TrackIds::Presentation), perfetto::ProcessTrack::Current()),
          choreographerThread(&PresentationEngine::ChoreographerThread, this),
          vsyncEvent(std::make_shared<kernel::type::KEvent>(state, true)) {
        auto desc{presentationTrack.Serialize()};
        desc.set_name("Presentation");
        perfetto::TrackEvent::SetTrackDescriptor(presentationTrack, desc);
    }

    PresentationEngine::~PresentationEngine() {
        auto env{state.jvm->GetEnv()};
        if (!env->IsSameObject(jSurface, nullptr))
            env->DeleteGlobalRef(jSurface);

        if (choreographerThread.joinable()) {
            if (choreographerLooper) {
                choreographerStop = true;
                ALooper_wake(choreographerLooper);
            }
            choreographerThread.join();
        }
    }

    void PresentationEngine::ChoreographerCallback(int64_t frameTimeNanos, PresentationEngine *engine) {
        // If the duration of this cycle deviates by ±0.5ms from the current refresh cycle duration then we reevaluate it
        i64 cycleLength{frameTimeNanos - engine->lastChoreographerTime};
        if (std::abs(cycleLength - engine->refreshCycleDuration) > (constant::NsInMillisecond / 2)) {
            if (engine->window)
                engine->window->perform(engine->window, NATIVE_WINDOW_GET_REFRESH_CYCLE_DURATION, &engine->refreshCycleDuration);
            else
                engine->refreshCycleDuration = cycleLength;
        }

        // Record the current cycle's timestamp and signal the V-Sync event to notify the game that a frame has been displayed
        engine->lastChoreographerTime = frameTimeNanos;
        engine->vsyncEvent->Signal();

        // Post the frame callback to be triggered on the next display refresh
        AChoreographer_postFrameCallback64(AChoreographer_getInstance(), reinterpret_cast<AChoreographer_frameCallback64>(&ChoreographerCallback), engine);
    }

    void PresentationEngine::ChoreographerThread() {
        if (int result{pthread_setname_np(pthread_self(), "Sky-Choreo")})
            Logger::Warn("Failed to set the thread name: {}", strerror(result));

        try {
            signal::SetSignalHandler({SIGINT, SIGILL, SIGTRAP, SIGBUS, SIGFPE, SIGSEGV}, signal::ExceptionalSignalHandler);
            choreographerLooper = ALooper_prepare(0);
            AChoreographer_postFrameCallback64(AChoreographer_getInstance(), reinterpret_cast<AChoreographer_frameCallback64>(&ChoreographerCallback), this);
            while (ALooper_pollAll(-1, nullptr, nullptr, nullptr) == ALOOPER_POLL_WAKE && !choreographerStop); // Will block and process callbacks till ALooper_wake() is called with choreographerStop set
        } catch (const signal::SignalException &e) {
            Logger::Error("{}\nStack Trace:{}", e.what(), state.loader->GetStackTrace(e.frames));
            if (state.process)
                state.process->Kill(false);
            else
                std::rethrow_exception(std::current_exception());
        } catch (const std::exception &e) {
            Logger::Error(e.what());
            if (state.process)
                state.process->Kill(false);
            else
                std::rethrow_exception(std::current_exception());
        }
    }

    NativeWindowTransform GetAndroidTransform(vk::SurfaceTransformFlagBitsKHR transform) {
        using NativeWindowTransform = NativeWindowTransform;
        switch (transform) {
            case vk::SurfaceTransformFlagBitsKHR::eIdentity:
            case vk::SurfaceTransformFlagBitsKHR::eInherit:
                return NativeWindowTransform::Identity;
            case vk::SurfaceTransformFlagBitsKHR::eRotate90:
                return NativeWindowTransform::Rotate90;
            case vk::SurfaceTransformFlagBitsKHR::eRotate180:
                return NativeWindowTransform::Rotate180;
            case vk::SurfaceTransformFlagBitsKHR::eRotate270:
                return NativeWindowTransform::Rotate270;
            case vk::SurfaceTransformFlagBitsKHR::eHorizontalMirror:
                return NativeWindowTransform::MirrorHorizontal;
            case vk::SurfaceTransformFlagBitsKHR::eHorizontalMirrorRotate90:
                return NativeWindowTransform::MirrorHorizontalRotate90;
            case vk::SurfaceTransformFlagBitsKHR::eHorizontalMirrorRotate180:
                return NativeWindowTransform::MirrorVertical;
            case vk::SurfaceTransformFlagBitsKHR::eHorizontalMirrorRotate270:
                return NativeWindowTransform::MirrorVerticalRotate90;
        }
    }

    void PresentationEngine::UpdateSwapchain(texture::Format format, texture::Dimensions extent) {
        auto minImageCount{std::max(vkSurfaceCapabilities.minImageCount, *state.settings->forceTripleBuffering ? 3U : 2U)};
        if (minImageCount > MaxSwapchainImageCount)
            throw exception("Requesting swapchain with higher image count ({}) than maximum slot count ({})", minImageCount, MaxSwapchainImageCount);

        const auto &capabilities{vkSurfaceCapabilities};
        if (minImageCount < capabilities.minImageCount || (capabilities.maxImageCount && minImageCount > capabilities.maxImageCount))
            throw exception("Cannot update swapchain to accomodate image count: {} ({}-{})", minImageCount, capabilities.minImageCount, capabilities.maxImageCount);
        else if (capabilities.minImageExtent.height > extent.height || capabilities.minImageExtent.width > extent.width || capabilities.maxImageExtent.height < extent.height || capabilities.maxImageExtent.width < extent.width)
            throw exception("Cannot update swapchain to accomodate image extent: {}x{} ({}x{}-{}x{})", extent.width, extent.height, capabilities.minImageExtent.width, capabilities.minImageExtent.height, capabilities.maxImageExtent.width, capabilities.maxImageExtent.height);

        vk::Format vkFormat{*format};
        if (swapchainFormat != format) {
            auto formats{gpu.vkPhysicalDevice.getSurfaceFormatsKHR(**vkSurface)};
            if (std::find(formats.begin(), formats.end(), vk::SurfaceFormatKHR{vkFormat, vk::ColorSpaceKHR::eSrgbNonlinear}) == formats.end())
                Logger::Warn("Surface doesn't support requested image format '{}' with colorspace '{}'", vk::to_string(vkFormat), vk::to_string(vk::ColorSpaceKHR::eSrgbNonlinear));
        }

        constexpr vk::ImageUsageFlags presentUsage{vk::ImageUsageFlagBits::eColorAttachment | vk::ImageUsageFlagBits::eTransferSrc | vk::ImageUsageFlagBits::eTransferDst};
        if ((capabilities.supportedUsageFlags & presentUsage) != presentUsage)
            throw exception("Swapchain doesn't support image usage '{}': {}", vk::to_string(presentUsage), vk::to_string(capabilities.supportedUsageFlags));

        auto requestedMode{*state.settings->disableFrameThrottling ? vk::PresentModeKHR::eMailbox : vk::PresentModeKHR::eFifo};
        auto modes{gpu.vkPhysicalDevice.getSurfacePresentModesKHR(**vkSurface)};
        if (std::find(modes.begin(), modes.end(), requestedMode) == modes.end())
            throw exception("Swapchain doesn't support present mode: {}", vk::to_string(requestedMode));

        vkSwapchain.emplace(gpu.vkDevice, vk::SwapchainCreateInfoKHR{
            .surface = **vkSurface,
            .minImageCount = minImageCount,
            .imageFormat = vkFormat,
            .imageColorSpace = vk::ColorSpaceKHR::eSrgbNonlinear,
            .imageExtent = extent,
            .imageArrayLayers = 1,
            .imageUsage = presentUsage,
            .imageSharingMode = vk::SharingMode::eExclusive,
            .compositeAlpha = vk::CompositeAlphaFlagBitsKHR::eInherit,
            .presentMode = requestedMode,
            .clipped = true,
        });

        auto vkImages{vkSwapchain->getImages()};
        if (vkImages.size() > MaxSwapchainImageCount)
            throw exception("Swapchain has higher image count ({}) than maximum slot count ({})", minImageCount, MaxSwapchainImageCount);

        for (size_t index{}; index < vkImages.size(); index++) {
            auto &slot{images[index]};
            slot = std::make_shared<Texture>(*state.gpu, vkImages[index], extent, format, vk::ImageLayout::eUndefined, vk::ImageTiling::eOptimal, vk::ImageCreateFlags{}, presentUsage);
            slot->TransitionLayout(vk::ImageLayout::ePresentSrcKHR);
        }
        for (size_t index{vkImages.size()}; index < MaxSwapchainImageCount; index++)
            // We need to clear all the slots which aren't filled, keeping around stale slots could lead to issues
            images[index] = {};

        swapchainFormat = format;
        swapchainExtent = extent;
    }

    void PresentationEngine::UpdateSurface(jobject newSurface) {
        std::scoped_lock guard{mutex};

        auto env{state.jvm->GetEnv()};
        if (!env->IsSameObject(jSurface, nullptr)) {
            env->DeleteGlobalRef(jSurface);
            jSurface = nullptr;
        }
        if (!env->IsSameObject(newSurface, nullptr))
            jSurface = env->NewGlobalRef(newSurface);

        vkSwapchain.reset();

        if (jSurface) {
            window = ANativeWindow_fromSurface(env, jSurface);
            vkSurface.emplace(gpu.vkInstance, vk::AndroidSurfaceCreateInfoKHR{
                .window = window,
            });
            if (!gpu.vkPhysicalDevice.getSurfaceSupportKHR(gpu.vkQueueFamilyIndex, **vkSurface))
                throw exception("Vulkan Queue doesn't support presentation with surface");
            vkSurfaceCapabilities = gpu.vkPhysicalDevice.getSurfaceCapabilitiesKHR(**vkSurface);

            if (swapchainExtent && swapchainFormat)
                UpdateSwapchain(swapchainFormat, swapchainExtent);

            if (window->common.magic != AndroidNativeWindowMagic)
                throw exception("ANativeWindow* has unexpected magic: {} instead of {}", span(&window->common.magic, 1).as_string(true), span<const u8>(reinterpret_cast<const u8 *>(&AndroidNativeWindowMagic), sizeof(u32)).as_string(true));
            if (window->common.version != sizeof(ANativeWindow))
                throw exception("ANativeWindow* has unexpected version: {} instead of {}", window->common.version, sizeof(ANativeWindow));

            int result;
            if (windowCrop && (result = window->perform(window, NATIVE_WINDOW_SET_CROP, &windowCrop)))
                throw exception("Setting the layer crop to ({}-{})x({}-{}) failed with {}", windowCrop.left, windowCrop.right, windowCrop.top, windowCrop.bottom, result);

            if (windowScalingMode != NativeWindowScalingMode::ScaleToWindow && (result = window->perform(window, NATIVE_WINDOW_SET_SCALING_MODE, static_cast<i32>(windowScalingMode))))
                throw exception("Setting the layer scaling mode to '{}' failed with {}", ToString(windowScalingMode), result);

            if (windowTransform != NativeWindowTransform::Identity && (result = window->perform(window, NATIVE_WINDOW_SET_BUFFERS_TRANSFORM, static_cast<i32>(windowTransform))))
                throw exception("Setting the buffer transform to '{}' failed with {}", ToString(windowTransform), result);

            if ((result = window->perform(window, NATIVE_WINDOW_ENABLE_FRAME_TIMESTAMPS, true)))
                throw exception("Enabling frame timestamps failed with {}", result);

            surfaceCondition.notify_all();
        } else {
            vkSurface.reset();
            window = nullptr;
        }
    }

    void PresentationEngine::Present(const std::shared_ptr<Texture> &texture, i64 timestamp, u64 swapInterval, AndroidRect crop, NativeWindowScalingMode scalingMode, NativeWindowTransform transform, u64 &frameId) {
        std::unique_lock lock(mutex);
        surfaceCondition.wait(lock, [this]() { return vkSurface.has_value(); });

        std::scoped_lock textureLock(*texture);
        if (texture->format != swapchainFormat || texture->dimensions != swapchainExtent)
            UpdateSwapchain(texture->format, texture->dimensions);

        int result;
        if (crop && crop != windowCrop) {
            if ((result = window->perform(window, NATIVE_WINDOW_SET_CROP, &crop)))
                throw exception("Setting the layer crop to ({}-{})x({}-{}) failed with {}", crop.left, crop.right, crop.top, crop.bottom, result);
            windowCrop = crop;
        }

        if (scalingMode != NativeWindowScalingMode::Freeze && windowScalingMode != scalingMode) {
            if ((result = window->perform(window, NATIVE_WINDOW_SET_SCALING_MODE, static_cast<i32>(scalingMode))))
                throw exception("Setting the layer scaling mode to '{}' failed with {}", ToString(scalingMode), result);
            windowScalingMode = scalingMode;
        }

        if (transform != windowTransform) {
            if ((result = window->perform(window, NATIVE_WINDOW_SET_BUFFERS_TRANSFORM, static_cast<i32>(transform))))
                throw exception("Setting the buffer transform to '{}' failed with {}", ToString(transform), result);
            windowTransform = transform;
        }

        gpu.vkDevice.resetFences(*acquireFence);

        std::pair<vk::Result, u32> nextImage;
        while (nextImage = vkSwapchain->acquireNextImage(std::numeric_limits<u64>::max(), {}, *acquireFence), nextImage.first != vk::Result::eSuccess) [[unlikely]] {
            if (nextImage.first == vk::Result::eSuboptimalKHR)
                surfaceCondition.wait(lock, [this]() { return vkSurface.has_value(); });
            else
                throw exception("vkAcquireNextImageKHR returned an unhandled result '{}'", vk::to_string(nextImage.first));
        }

        std::ignore = gpu.vkDevice.waitForFences(*acquireFence, true, std::numeric_limits<u64>::max());

        texture->SynchronizeHost();
        images.at(nextImage.second)->CopyFrom(texture, vk::ImageSubresourceRange{
            .aspectMask = vk::ImageAspectFlagBits::eColor,
            .levelCount = 1,
            .layerCount = 1,
        });

        if (timestamp) {
            // If the timestamp is specified, we need to convert it from the util::GetTimeNs base to the CLOCK_MONOTONIC one
            // We do so by getting an offset from the current time in nanoseconds and then adding it to the current time in CLOCK_MONOTONIC
            // Note: It's important we do this right before present as going past the timestamp could lead to fewer Binder IPC calls
            i64 current{util::GetTimeNs()};
            if (current < timestamp) {
                timespec time;
                if (clock_gettime(CLOCK_MONOTONIC, &time))
                    throw exception("Failed to clock_gettime with '{}'", strerror(errno));
                timestamp = ((time.tv_sec * constant::NsInSecond) + time.tv_nsec) + (timestamp - current);
            } else {
                timestamp = 0;
            }
        }

        if (swapInterval > 1)
            // If we have a swap interval above 1 we have to adjust the timestamp to emulate the swap interval
            timestamp = std::max(timestamp, lastChoreographerTime + (refreshCycleDuration * static_cast<i64>(swapInterval) * 2));

        auto lastTimestamp{std::exchange(windowLastTimestamp, timestamp)};
        if (!timestamp && lastTimestamp)
            // We need to nullify the timestamp if it transitioned from being specified (non-zero) to unspecified (zero)
            timestamp = NativeWindowTimestampAuto;

        if (timestamp && (result = window->perform(window, NATIVE_WINDOW_SET_BUFFERS_TIMESTAMP, timestamp)))
            throw exception("Setting the buffer timestamp to {} failed with {}", timestamp, result);

        if ((result = window->perform(window, NATIVE_WINDOW_GET_NEXT_FRAME_ID, &frameId)))
            throw exception("Retrieving the next frame's ID failed with {}", result);

        {
            std::scoped_lock queueLock{gpu.queueMutex};
            std::ignore = gpu.vkQueue.presentKHR(vk::PresentInfoKHR{
                .swapchainCount = 1,
                .pSwapchains = &**vkSwapchain,
                .pImageIndices = &nextImage.second,
            }); // We don't care about suboptimal images as they are caused by not respecting the transform hint, we handle transformations externally
        }

        if (frameTimestamp) {
            i64 now{util::GetTimeNs()};
            i64 sampleWeight{swapInterval ? constant::NsInSecond / (refreshCycleDuration * static_cast<i64>(swapInterval)) : 10}; //!< The weight of each sample in calculating the average, we arbitrarily average 10 samples for unlocked FPS

            auto weightedAverage{[](auto weight, auto previousAverage, auto current) {
                return (((weight - 1) * previousAverage) + current) / weight;
            }}; //!< Modified moving average (https://en.wikipedia.org/wiki/Moving_average#Modified_moving_average)

            i64 currentFrametime{now - frameTimestamp};
            averageFrametimeNs = weightedAverage(sampleWeight, averageFrametimeNs, currentFrametime);
            AverageFrametimeMs = static_cast<jfloat>(averageFrametimeNs) / constant::NsInMillisecond;

            i64 currentFrametimeDeviation{std::abs(averageFrametimeNs - currentFrametime)};
            averageFrametimeDeviationNs = weightedAverage(sampleWeight, averageFrametimeDeviationNs, currentFrametimeDeviation);
            AverageFrametimeDeviationMs = static_cast<jfloat>(averageFrametimeDeviationNs) / constant::NsInMillisecond;

            Fps = static_cast<jint>(std::round(static_cast<float>(constant::NsInSecond) / static_cast<float>(averageFrametimeNs)));

            TRACE_EVENT_INSTANT("gpu", "Present", presentationTrack, "FrameTimeNs", now - frameTimestamp, "Fps", Fps);

            frameTimestamp = now;
        } else {
            frameTimestamp = util::GetTimeNs();
        }
    }

    NativeWindowTransform PresentationEngine::GetTransformHint() {
        std::unique_lock lock(mutex);
        surfaceCondition.wait(lock, [this]() { return vkSurface.has_value(); });
        return GetAndroidTransform(vkSurfaceCapabilities.currentTransform);
    }
}