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#include "timestamp_pool.hh"
#include "device_context.hh"
#include "queue_context.hh"
#include <ranges>
#include <vulkan/utility/vk_dispatch_table.h>
#include <vulkan/vulkan_core.h>
namespace low_latency {
TimestampPool::QueryChunk::QueryChunk(const QueueContext& queue_context) {
const auto& device_context = queue_context.device_context;
const auto& vtable = device_context.vtable;
this->query_pool = [&]() {
const auto qpci = VkQueryPoolCreateInfo{
.sType = VK_STRUCTURE_TYPE_QUERY_POOL_CREATE_INFO,
.queryType = VK_QUERY_TYPE_TIMESTAMP,
.queryCount = QueryChunk::CHUNK_SIZE};
auto qp = VkQueryPool{};
vtable.CreateQueryPool(device_context.device, &qpci, nullptr, &qp);
return qp;
}();
constexpr auto key_range = std::views::iota(0u, QueryChunk::CHUNK_SIZE);
this->free_indices = std::make_unique<free_indices_t>(std::begin(key_range),
std::end(key_range));
this->command_buffers = [&, this]() -> auto {
auto cbs = std::make_unique<std::vector<VkCommandBuffer>>(CHUNK_SIZE);
const auto cbai = VkCommandBufferAllocateInfo{
.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_ALLOCATE_INFO,
.commandPool = queue_context.command_pool,
.level = VK_COMMAND_BUFFER_LEVEL_PRIMARY,
.commandBufferCount = static_cast<std::uint32_t>(std::size(*cbs)),
};
vtable.AllocateCommandBuffers(device_context.device, &cbai,
std::data(*cbs));
return cbs;
}();
}
TimestampPool::QueryChunk::~QueryChunk() {}
TimestampPool::TimestampPool(QueueContext& queue_context)
: queue_context(queue_context) {
// Allocate one block on construction, it's likely more than enough.
auto query_chunk = std::make_shared<QueryChunk>(this->queue_context);
this->query_chunks.emplace(std::move(query_chunk));
}
std::shared_ptr<TimestampPool::Handle> TimestampPool::acquire() {
// Gets the empty one, or inserts a new one and returns it.
const auto not_empty_iter = [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 insert = std::make_shared<QueryChunk>(this->queue_context);
const auto [iter, did_insert] = this->query_chunks.emplace(insert);
assert(did_insert);
return iter;
}();
// Grab any element from our set and erase it immediately after.
auto& indices = *(*not_empty_iter)->free_indices;
const auto query_index = *std::begin(indices);
assert(indices.erase(query_index));
return std::make_shared<Handle>(*this, *not_empty_iter, query_index);
}
TimestampPool::Handle::Handle(const TimestampPool& timestamp_pool,
const std::shared_ptr<QueryChunk>& origin_chunk,
const std::uint64_t& query_index)
: timestamp_pool(timestamp_pool), query_pool(origin_chunk->query_pool),
query_index(query_index), origin_chunk(origin_chunk),
command_buffer((*origin_chunk->command_buffers)[query_index]) {}
TimestampPool::Handle::~Handle() {
// Parent destructing shouldn't mean we should have a bunch of
// insertions for zero reason.
if (const auto ptr = this->origin_chunk.lock(); ptr) {
assert(ptr->free_indices->insert(this->query_index).second);
}
}
void TimestampPool::Handle::setup_command_buffers(
const Handle& tail, const QueueContext& queue_context) const {
const auto cbbi = VkCommandBufferBeginInfo{
.sType = VK_STRUCTURE_TYPE_COMMAND_BUFFER_BEGIN_INFO,
};
const auto& device_context = queue_context.device_context;
const auto& vtable = device_context.vtable;
vtable.ResetQueryPoolEXT(device_context.device, this->query_pool,
this->query_index, 1);
vtable.BeginCommandBuffer(this->command_buffer, &cbbi);
vtable.CmdWriteTimestamp2KHR(this->command_buffer,
VK_PIPELINE_STAGE_2_TOP_OF_PIPE_BIT,
this->query_pool, this->query_index);
vtable.EndCommandBuffer(this->command_buffer);
vtable.ResetQueryPoolEXT(device_context.device, tail.query_pool,
tail.query_index, 1);
vtable.ResetCommandBuffer(tail.command_buffer, 0);
vtable.BeginCommandBuffer(tail.command_buffer, &cbbi);
vtable.CmdWriteTimestamp2KHR(tail.command_buffer,
VK_PIPELINE_STAGE_2_BOTTOM_OF_PIPE_BIT,
tail.query_pool, tail.query_index);
vtable.EndCommandBuffer(tail.command_buffer);
}
DeviceContext::Clock::time_point_t TimestampPool::Handle::get_time() {
const auto& device_ctx = this->timestamp_pool.queue_context.device_context;
const auto& vtable = device_ctx.vtable;
// For debug builds, we're going to query the availability bit so we can
// assert that after the semaphore has flagged it as naturally available.
struct QueryResult {
std::uint64_t value;
#ifndef NDEBUG
std::uint64_t available;
#endif
};
auto query_result = QueryResult{};
constexpr auto query_flags = []() -> auto {
auto flag = VkQueryResultFlags{VK_QUERY_RESULT_64_BIT};
#ifndef NDEBUG
flag |= VK_QUERY_RESULT_WITH_AVAILABILITY_BIT;
#endif
return flag;
}();
const auto r = vtable.GetQueryPoolResults(
device_ctx.device, query_pool, this->query_index, 1,
sizeof(query_result), &query_result, sizeof(query_result), query_flags);
assert(r == VK_SUCCESS && query_result.available);
return device_ctx.clock.ticks_to_time(query_result.value);
}
TimestampPool::~TimestampPool() {
const auto& device = this->queue_context.device_context.device;
const auto& vtable = this->queue_context.device_context.vtable;
for (const auto& query_chunk : this->query_chunks) {
vtable.FreeCommandBuffers(device, this->queue_context.command_pool,
std::size(*query_chunk->command_buffers),
std::data(*query_chunk->command_buffers));
vtable.DestroyQueryPool(device, query_chunk->query_pool, nullptr);
}
}
} // namespace low_latency
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