response_base.hpp

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#pragma once
 
/// @file userver/server/request/response_base.hpp
/// @brief @copybrief server::request::ResponseBase
 
#include <atomic>
#include <chrono>
#include <functional>
#include <limits>
#include <optional>
#include <string>
 
#include <userver/concurrent/queue.hpp>
#include <userver/concurrent/striped_counter.hpp>
#include <userver/engine/single_consumer_event.hpp>
#include <userver/utils/fast_pimpl.hpp>
 
USERVER_NAMESPACE_BEGIN
 
/// @cond
// TODO: server internals. remove from a public interface
namespace server::http::impl {
 
struct Http2StreamEvent {
    std::int32_t stream_id{-1};
    std::string body_part{};
    bool is_end{false};
};
 
// The order is fifo in the context of a single producer. So we are tolerant to
// reordering between producers
using Http2StreamEventQueue = concurrent::NonFifoMpscQueue<Http2StreamEvent>;
 
class Http2StreamEventProducer final {
public:
    Http2StreamEventProducer(Http2StreamEventQueue& queue, engine::SingleConsumerEvent& event);
 
    void PushEvent(Http2StreamEvent event, engine::Deadline deadline = {});
 
    void CloseStream(std::int32_t id);
 
private:
    Http2StreamEventQueue::Producer producer_;
    engine::SingleConsumerEvent& event_;
};
 
}  // namespace server::http::impl
/// @endcond
 
namespace engine::io {
class RwBase;
}  // namespace engine::io
 
namespace server::request {
 
class ResponseDataAccounter final {
public:
    void StartRequest(std::chrono::steady_clock::time_point create_time);
 
    void StopRequest(std::size_t size, std::chrono::steady_clock::time_point create_time);
 
    void ReaccountRequest(
        std::size_t old_size,
        std::chrono::steady_clock::time_point old_create_time,
        std::size_t new_size,
        std::chrono::steady_clock::time_point new_create_time
    );
 
    std::size_t GetPendingResponsesSizeInBytes() const { return pending_responses_size_in_bytes_; }
 
    std::size_t GetPendingResponsesCount() const { return pending_responses_count_.NonNegativeRead(); }
 
    std::size_t GetMaxPendingResponsesSizeInBytes() const { return max_pending_responses_size_in_bytes_; }
 
    void SetMaxPendingResponsesSizeInBytes(size_t size) { max_pending_responses_size_in_bytes_ = size; }
 
    std::chrono::milliseconds GetAvgRequestTime() const;
 
private:
    std::atomic<std::size_t> pending_responses_size_in_bytes_{0};
    std::atomic<std::size_t> max_pending_responses_size_in_bytes_{std::numeric_limits<std::size_t>::max()};
    concurrent::StripedCounter pending_responses_count_{};
    concurrent::StripedCounter time_sum_{};
};
 
// TODO: merge with HttpResponse
 
/// @brief Base class for all the server responses.
class ResponseBase {
public:
    explicit ResponseBase(ResponseDataAccounter& data_accounter);
    ResponseBase(const ResponseBase&) = delete;
    ResponseBase(ResponseBase&&) = delete;
    virtual ~ResponseBase() noexcept;
 
    void SetData(std::string data);
    const std::string& GetData() const { return data_; }
    std::string&& ExtractData() { return std::move(data_); }
 
    virtual bool IsBodyStreamed() const = 0;
    virtual bool WaitForHeadersEnd() = 0;
    virtual void SetHeadersEnd() = 0;
 
    /// @cond
    // TODO: server internals. remove from a public interface
    void SetReady();
    void SetReady(std::chrono::steady_clock::time_point now);
    virtual void SetSendFailed(std::chrono::steady_clock::time_point failure_time);
    bool IsLimitReached() const;
 
    bool IsReady() const { return ready_time_ != kUnset; }
    bool IsSent() const noexcept { return sent_time_ != kUnset; }
    size_t BytesSent() const { return bytes_sent_; }
    std::chrono::steady_clock::time_point ReadyTime() const { return ready_time_; }
    std::chrono::steady_clock::time_point SentTime() const { return sent_time_; }
    virtual void SendResponse(engine::io::RwBase& socket) = 0;
 
    virtual void SetStatusServiceUnavailable() = 0;
    virtual void SetStatusOk() = 0;
    virtual void SetStatusNotFound() = 0;
 
    // HTTP/2.0 only
    void SetStreamId(std::int32_t stream_id);
    std::optional<std::int32_t> GetStreamId() const { return stream_id_; }
    void SetStreamProdicer(http::impl::Http2StreamEventProducer&& producer);
    http::impl::Http2StreamEventProducer GetStreamProducer();
    /// @endcond
 
protected:
    ResponseBase(ResponseDataAccounter& data_account, std::chrono::steady_clock::time_point now);
 
    void SetSent(std::size_t bytes_sent, std::chrono::steady_clock::time_point sent_time);
 
private:
    static constexpr auto kUnset = std::chrono::steady_clock::time_point::min();
 
    ResponseDataAccounter& accounter_;
    std::string data_;
    std::chrono::steady_clock::time_point create_time_;
    std::chrono::steady_clock::time_point ready_time_{kUnset};
    std::chrono::steady_clock::time_point sent_time_{kUnset};
    std::size_t accounted_size_ = 0;
    size_t bytes_sent_ = 0;
    std::optional<std::int32_t> stream_id_;
    std::optional<http::impl::Http2StreamEventProducer> producer_{};
};
 
}  // namespace server::request
 
USERVER_NAMESPACE_END