cancel.h

#pragma once
 
#include <ozo/connection.h>
#include <ozo/time_traits.h>
 
#include <libpq-fe.h>
#include <memory>
 
namespace ozo {
 
template <typename Executor>
class cancel_handle {
public:
    using executor_type = std::decay_t<Executor>; 
 
    executor_type get_executor() const { return std::get<1>(v_);} 
 
    using native_handle_type = PGcancel*; 
 
    native_handle_type native_handle() const { return std::get<0>(v_).get();} 
 
    cancel_handle(native_handle_type handle, Executor ex) : v_(handle, std::move(ex)) {}
 
private:
    struct deleter {
        void operator()(native_handle_type h) const { PQfreeCancel(h); }
    };
 
    std::tuple<std::unique_ptr<PGcancel, deleter>, executor_type> v_;
};
 
template <typename Connection, typename Executor = boost::asio::system_executor>
inline cancel_handle<Executor> get_cancel_handle(const Connection& connection, Executor&& executor = Executor{});
 
#ifdef OZO_DOCUMENTATION
 
 
template <typename Executor, typename TimeConstraint, typename CancelCompletionToken>
auto cancel(cancel_handle<Executor>&& handle, io_context& io, TimeConstraint time_constraint, CancelCompletionToken&& token);
 
template <typename Executor, typename CancelCompletionToken>
auto cancel(cancel_handle<Executor>&& handle, CancelCompletionToken&& token);
#else
struct cancel_op {
    template <typename Executor, typename TimeConstraint, typename CancelCompletionToken>
    auto operator() (cancel_handle<Executor>&& handle, io_context& io,
        TimeConstraint time_constraint, CancelCompletionToken&& token) const;
 
    template <typename Executor, typename CancelCompletionToken>
    auto operator() (cancel_handle<Executor>&& handle, CancelCompletionToken&& token) const;
};
 
constexpr cancel_op cancel;
 
#endif
} // namespace ozo
 
#include <ozo/impl/cancel.h>