io_policy.hpp

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#ifndef JOIN_CORE_IO_POLICY_HPP
#define JOIN_CORE_IO_POLICY_HPP
 
// C.
#include <liburing.h>
#include <cstdint>
 
namespace join
{
    struct IoDefaultPolicy
    {
        static constexpr uint32_t sqEntries = 1024;
        static constexpr uint32_t flags = 0;
    };
 
    struct IoHybridPolicy
    {
        static constexpr uint32_t sqEntries = 1024;
        static constexpr uint32_t flags = 0;
        static constexpr uint32_t spin = 200;
    };
 
    struct IoSqpollPolicy
    {
        static constexpr uint32_t sqEntries = 1024;
        static constexpr uint32_t flags = IORING_SETUP_SQPOLL;
        static constexpr uint32_t spin = 200;
        static constexpr uint32_t sqThreadIdle = 2000;
        static constexpr uint32_t sqThreadCpu = 0;
    };
 
    template <typename...>
    using void_t = void;
 
    template <typename T, typename = void>
    struct has_spin : std::false_type
    {
    };
 
    template <typename T>
    struct has_spin<T, void_t<decltype (T::spin)>> : std::true_type
    {
    };
 
    template <typename T, typename = void>
    struct has_sqpoll : std::false_type
    {
    };
 
    template <typename T>
    struct has_sqpoll<T, void_t<decltype (T::flags)>>
    : std::integral_constant<bool, bool (T::flags& IORING_SETUP_SQPOLL)>
    {
    };
 
    template <typename T>
    struct is_default : std::integral_constant<bool, !has_spin<T>::value && !has_sqpoll<T>::value>
    {
    };
 
    template <typename T, typename = void>
    struct has_cq_entries : std::false_type
    {
    };
 
    template <typename T>
    struct has_cq_entries<T, void_t<decltype (T::cqEntries)>> : std::true_type
    {
    };
 
    template <typename T, typename = void>
    struct has_sq_thread_idle : std::false_type
    {
    };
 
    template <typename T>
    struct has_sq_thread_idle<T, void_t<decltype (T::sqThreadIdle)>> : std::true_type
    {
    };
 
    template <typename T, typename = void>
    struct has_sq_thread_cpu : std::false_type
    {
    };
 
    template <typename T>
    struct has_sq_thread_cpu<T, void_t<decltype (T::sqThreadCpu)>> : std::true_type
    {
    };
}
 
#endif