io_uring.h

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#pragma once
 
#include "di/sync/prelude.h"
#include "di/vocab/error/prelude.h"
#include "dius/memory_region.h"
#include "dius/sync_file.h"
 
namespace dius::linux {
namespace io_uring {
    using SQE = struct io_uring_sqe;
    using CQE = struct io_uring_cqe;
    using SetupParams = struct io_uring_params;
 
    auto sys_enter(unsigned int fd, unsigned int to_submit, unsigned int min_complete, unsigned int flags,
                   void const* arg, size_t arg_size) -> di::Result<int>;
    auto sys_register(unsigned int fd, unsigned int op_code, void* arg, unsigned int nr_args) -> di::Result<int>;
    auto sys_setup(u32 entries, SetupParams* params) -> di::Result<SyncFile>;
 
    class IoUringHandle {
    public:
        static auto create() -> di::Result<IoUringHandle>;
 
        auto get_next_sqe() -> di::Optional<SQE&>;
        auto get_next_cqe() -> di::Optional<CQE&>;
 
        auto submit_and_wait() -> di::Result<void>;
 
    private:
        IoUringHandle() = default;
 
        u32 sq_entry_count;
        u32 sq_mask;
        u32* sq_index_array;
        SQE* sq_array;
 
        di::Atomic<unsigned int> const* sq_head;
        di::Atomic<unsigned int>* sq_tail;
        di::Atomic<unsigned int> const* sq_flags;
 
        u32 cq_entry_count;
        u32 cq_mask;
        CQE* cq_array;
 
        di::Atomic<unsigned int>* cq_head;
        di::Atomic<unsigned int> const* cq_tail;
        di::Atomic<unsigned int> const* cq_overflow;
 
        SyncFile fd;
        MemoryRegion sq_region;
        MemoryRegion sqe_region;
        MemoryRegion cq_region;
 
        u32 sq_pending { 0 };
    };
}
}