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#include "swapchain_monitor.hh"
#include "device_context.hh"
#include "helper.hh"
#include <functional>
namespace low_latency {
SwapchainMonitor::SwapchainMonitor(const DeviceContext& device)
: device(device),
monitor_worker(std::bind_front(&SwapchainMonitor::do_monitor, this)) {}
SwapchainMonitor::~SwapchainMonitor() {}
void SwapchainMonitor::WakeupSemaphore::signal(
const DeviceContext& device) const {
const auto ssi =
VkSemaphoreSignalInfo{.sType = VK_STRUCTURE_TYPE_SEMAPHORE_SIGNAL_INFO,
.semaphore = this->timeline_semaphore,
.value = this->value};
THROW_NOT_VKSUCCESS(device.vtable.SignalSemaphore(device.device, &ssi));
}
void SwapchainMonitor::update_params(const bool was_low_latency_requested,
const std::chrono::microseconds delay) {
const auto lock = std::scoped_lock{this->mutex};
this->was_low_latency_requested = was_low_latency_requested;
this->present_delay = delay;
}
void SwapchainMonitor::do_monitor(const std::stop_token stoken) {
for (;;) {
auto lock = std::unique_lock{this->mutex};
this->cv.wait(lock, stoken,
[&]() { return !this->pending_signals.empty(); });
// Stop only if we're stopped and we have nothing to signal.
if (stoken.stop_requested() && this->pending_signals.empty()) {
break;
}
// Grab the most recent semaphore. When work completes, signal it.
const auto pending_signal = std::move(this->pending_signals.front());
this->pending_signals.pop_front();
// If we're stopping, signal the semaphore and don't worry about work
// actually completing.
if (stoken.stop_requested()) {
pending_signal.wakeup_semaphore.signal(this->device);
break;
}
// Unlock, wait for work to finish, lock again.
lock.unlock();
for (const auto& frame_span : pending_signal.frame_spans) {
if (frame_span) {
frame_span->await_completed();
}
}
lock.lock();
using namespace std::chrono;
if (this->present_delay != 0us) {
const auto last_time = this->last_signal_time;
const auto delay = this->present_delay;
if (last_time.has_value()) {
lock.unlock();
std::this_thread::sleep_until(*last_time + delay);
lock.lock();
}
this->last_signal_time.emplace(steady_clock::now());
}
lock.unlock();
pending_signal.wakeup_semaphore.signal(this->device);
}
}
void SwapchainMonitor::notify_semaphore(const VkSemaphore& timeline_semaphore,
const std::uint64_t& value) {
auto lock = std::unique_lock{this->mutex};
const auto wakeup_semaphore = WakeupSemaphore{
.timeline_semaphore = timeline_semaphore, .value = value};
// Signal immediately if reflex is off or it's a no-op submit.
if (!this->was_low_latency_requested) {
wakeup_semaphore.signal(this->device);
return;
}
// Signal immediately if we have no outstanding work.
if (std::ranges::all_of(this->pending_frame_spans,
[](const auto& frame_span) {
if (!frame_span) {
return true;
}
return frame_span->has_completed();
})) {
wakeup_semaphore.signal(this->device);
this->pending_frame_spans.clear();
return;
}
this->pending_signals.emplace_back(PendingSignal{
.wakeup_semaphore = wakeup_semaphore,
.frame_spans = std::move(this->pending_frame_spans),
});
this->pending_frame_spans.clear();
lock.unlock();
this->cv.notify_one();
}
void SwapchainMonitor::attach_work(
std::vector<std::unique_ptr<FrameSpan>> frame_spans) {
const auto lock = std::scoped_lock{this->mutex};
if (!this->was_low_latency_requested) {
return;
}
this->pending_frame_spans = std::move(frame_spans);
}
} // namespace low_latency
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