response_future.hpp

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#pragma once
 
/// @file userver/clients/http/response_future.hpp
/// @brief @copybrief clients::http::ResponseFuture
 
#include <future>
#include <memory>
 
#include <userver/clients/http/cancellation_policy.hpp>
#include <userver/clients/http/response.hpp>
#include <userver/compiler/impl/lifetime.hpp>
#include <userver/engine/awaitable.hpp>
#include <userver/engine/deadline.hpp>
#include <userver/engine/future.hpp>
#include <userver/utils/impl/source_location.hpp>
 
USERVER_NAMESPACE_BEGIN
 
namespace clients::http {
 
class RequestState;
 
namespace impl {
class EasyWrapper;
}  // namespace impl
 
/// @brief Allows to perform a request concurrently with other work without
/// creating an extra coroutine for waiting.
class ResponseFuture final {
public:
    ResponseFuture(ResponseFuture&& other) noexcept;
    ResponseFuture& operator=(ResponseFuture&&) noexcept;
    ResponseFuture(const ResponseFuture&) = delete;
    ResponseFuture& operator=(const ResponseFuture&) = delete;
    ~ResponseFuture();
 
    /// @brief Cancel the request in flight
    void Cancel();
 
    /// @brief Keep executing the request but do not care any more about the result. It is fine to destroy this future
    /// after Detach(), the request will continue execution.
    void Detach();
 
    /// @brief Stops the current task execution until the request finishes
    /// @throws clients::http::CancelException if the current task is being cancelled
    /// @returns std::future_status::ready or std::future_status::timeout
    std::future_status Wait(utils::impl::SourceLocation location = utils::impl::SourceLocation::Current());
 
    /// @brief Returns whether the response is already available.
    bool IsReady() const;
 
    /// @brief Wait for the response and return it
    std::shared_ptr<Response> Get(utils::impl::SourceLocation location = utils::impl::SourceLocation::Current());
 
    /// Satisfies @ref engine::Awaitable, for use with @ref engine::WaitAnyContext and friends.
    engine::AwaitableToken GetAwaitableToken() noexcept USERVER_IMPL_LIFETIME_BOUND;
 
    /// @cond
    ResponseFuture(engine::Future<std::shared_ptr<Response>>&& future, std::shared_ptr<RequestState> request);
    /// @endcond
 
private:
    void CancelOrDetach();
 
    engine::Future<std::shared_ptr<Response>> future_;
    engine::Deadline deadline_;
    std::shared_ptr<RequestState> request_state_;
    bool was_deadline_propagated_{false};
    CancellationPolicy cancellation_policy_;
};
 
}  // namespace clients::http
 
USERVER_NAMESPACE_END