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#include "timestamp_pool.hh"
#include "device_context.hh"
#include "helper.hh"
#include "queue_context.hh"
#include <functional>
#include <mutex>
#include <ranges>
#include <span>
#include <vulkan/utility/vk_dispatch_table.h>
#include <vulkan/vulkan_core.h>
namespace low_latency {
TimestampPool::QueryChunk::QueryPoolOwner::QueryPoolOwner(
const QueueContext& queue_context)
: queue_context(queue_context) {
const auto& device_context = this->queue_context.device;
const auto qpci =
VkQueryPoolCreateInfo{.sType = VK_STRUCTURE_TYPE_QUERY_POOL_CREATE_INFO,
.queryType = VK_QUERY_TYPE_TIMESTAMP,
.queryCount = QueryChunk::CHUNK_SIZE};
THROW_NOT_VKSUCCESS(device_context.vtable.CreateQueryPool(
device_context.device, &qpci, nullptr, &this->query_pool));
}
TimestampPool::QueryChunk::QueryPoolOwner::~QueryPoolOwner() {
const auto& device_context = this->queue_context.device;
device_context.vtable.DestroyQueryPool(device_context.device,
this->query_pool, nullptr);
}
TimestampPool::QueryChunk::QueryChunk(const QueueContext& queue_context)
: query_pool(std::make_unique<QueryPoolOwner>(queue_context)),
command_buffers(std::make_unique<CommandBuffersOwner>(queue_context)) {
this->free_indices = []() {
constexpr auto keys = std::views::iota(0u, QueryChunk::CHUNK_SIZE) |
std::views::stride(2u);
return std::unordered_set<std::uint32_t>(std::from_range, keys);
}();
}
TimestampPool::QueryChunk::CommandBuffersOwner::CommandBuffersOwner(
const QueueContext& queue_context)
: queue_context(queue_context), command_buffers(CHUNK_SIZE) {
const auto& device_context = queue_context.device;
const auto cbai = VkCommandBufferAllocateInfo{
.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO,
.commandPool = *queue_context.command_pool,
.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY,
.commandBufferCount = CHUNK_SIZE,
};
THROW_NOT_VKSUCCESS(device_context.vtable.AllocateCommandBuffers(
device_context.device, &cbai, std::data(this->command_buffers)));
}
TimestampPool::QueryChunk::CommandBuffersOwner::~CommandBuffersOwner() {
const auto& device_context = this->queue_context.device;
device_context.vtable.FreeCommandBuffers(
device_context.device, *this->queue_context.command_pool,
static_cast<std::uint32_t>(std::size(this->command_buffers)),
std::data(this->command_buffers));
}
TimestampPool::QueryChunk::~QueryChunk() {}
TimestampPool::TimestampPool(QueueContext& queue_context)
: queue_context(queue_context),
reaper_worker(std::bind_front(&TimestampPool::do_reaper, this)) {}
std::shared_ptr<TimestampPool::Handle> TimestampPool::acquire() {
const auto lock = std::scoped_lock{this->mutex};
// Gets the empty one, or inserts a new one and returns it.
auto& query_chunk = [this]() -> auto& {
const auto not_empty_iter =
std::ranges::find_if(this->query_chunks, [](const auto& qc) {
assert(qc);
return std::size(qc->free_indices);
});
if (not_empty_iter != std::end(this->query_chunks)) {
return **not_empty_iter;
}
const auto [iter, did_insert] = this->query_chunks.emplace(
std::make_unique<QueryChunk>(this->queue_context));
assert(did_insert);
return **iter;
}();
// Pull any element from our set to use as our query_index here.
const auto query_index = *std::begin(query_chunk.free_indices);
query_chunk.free_indices.erase(query_index);
// Custom deleter function that puts the handle on our async reaper queue.
const auto reaper_deleter = [this](Handle* const handle) {
if (!handle) {
return;
}
const auto lock = std::scoped_lock{this->mutex};
this->expiring_handles.push_back(handle);
this->cv.notify_one();
};
return std::shared_ptr<Handle>(new Handle(*this, query_chunk, query_index),
reaper_deleter);
}
TimestampPool::Handle::Handle(TimestampPool& timestamp_pool,
QueryChunk& query_chunk,
const std::uint32_t query_index)
: timestamp_pool(timestamp_pool), query_chunk(query_chunk),
query_index(query_index) {
const auto cbbi = VkCommandBufferBeginInfo{
.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO,
};
const auto& device_context = this->timestamp_pool.queue_context.device;
const auto& vtable = device_context.vtable;
const auto command_buffers =
std::data(this->query_chunk.command_buffers->command_buffers);
const auto rewrite_cmd = [&](const std::uint32_t offset,
const VkPipelineStageFlagBits2 bit) {
const auto& command_buffer = command_buffers[query_index + offset];
const auto& query_pool = *this->query_chunk.query_pool;
const auto index =
static_cast<std::uint32_t>(this->query_index) + offset;
vtable.ResetQueryPoolEXT(device_context.device, query_pool, index, 1);
THROW_NOT_VKSUCCESS(vtable.ResetCommandBuffer(command_buffer, 0));
THROW_NOT_VKSUCCESS(vtable.BeginCommandBuffer(command_buffer, &cbbi));
vtable.CmdWriteTimestamp2KHR(command_buffer, bit, query_pool, index);
THROW_NOT_VKSUCCESS(vtable.EndCommandBuffer(command_buffer));
};
rewrite_cmd(0, VK_PIPELINE_STAGE_2_TOP_OF_PIPE_BIT);
rewrite_cmd(1, VK_PIPELINE_STAGE_2_BOTTOM_OF_PIPE_BIT);
}
TimestampPool::Handle::~Handle() {}
void TimestampPool::do_reaper(const std::stop_token stoken) {
for (;;) {
auto lock = std::unique_lock{this->mutex};
this->cv.wait(lock, stoken,
[&]() { return !this->expiring_handles.empty(); });
// Keep going and free everything before destructing.
if (stoken.stop_requested() && this->expiring_handles.empty()) {
break;
}
const auto handle_ptr = this->expiring_handles.front();
this->expiring_handles.pop_front();
// Allow more to go on the queue while we wait for it to finish.
lock.unlock();
handle_ptr->await_end_time();
// Lock our mutex, allow the queue to use it again and delete it.
lock.lock();
handle_ptr->query_chunk.free_indices.insert(handle_ptr->query_index);
delete handle_ptr;
}
}
const VkCommandBuffer& TimestampPool::Handle::get_start_buffer() const {
const auto command_buffers =
std::data(this->query_chunk.command_buffers->command_buffers);
return command_buffers[this->query_index];
}
const VkCommandBuffer& TimestampPool::Handle::get_end_buffer() const {
const auto command_buffers =
std::data(this->query_chunk.command_buffers->command_buffers);
return command_buffers[this->query_index + 1];
}
DeviceClock::time_point_t
TimestampPool::Handle::await_time_impl(const std::uint32_t offset) const {
const auto& context = this->timestamp_pool.queue_context.device;
const auto& vtable = context.vtable;
const auto& query_pool = *this->query_chunk.query_pool;
auto query_result = std::array<std::uint64_t, 2>{};
THROW_NOT_VKSUCCESS(vtable.GetQueryPoolResults(
context.device, query_pool, this->query_index + offset, 1,
sizeof(query_result), &query_result, sizeof(query_result),
VK_QUERY_RESULT_64_BIT | VK_QUERY_RESULT_WITH_AVAILABILITY_BIT |
VK_QUERY_RESULT_WAIT_BIT));
assert(query_result[1]);
return context.clock->ticks_to_time(query_result[0]);
}
DeviceClock::time_point_t TimestampPool::Handle::await_start_time() const {
return this->await_time_impl(0);
}
DeviceClock::time_point_t TimestampPool::Handle::await_end_time() const {
return this->await_time_impl(1);
}
TimestampPool::~TimestampPool() {}
} // namespace low_latency
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