Linux 异步 I/O 框架 io_uring：基本原理、程序示例与性能压测

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <fcntl.h>
#include <unistd.h>
#include <liburing.h>
 
#define BUFFER_SIZE 1024
 
int main(int argc, char *argv[]) {
    if (argc != 2) {
        printf("Usage: %s <file>\n", argv[0]);
        return 1;
    }
 
    struct io_uring ring;
    if (io_uring_queue_init(8, &ring, 0) != 0) {
        perror("io_uring_queue_init");
        return 1;
    }
 
    int fd = open(argv[1], O_RDONLY | O_NONBLOCK);
    if (fd < 0) {
        perror("open");
        return 1;
    }
 
    char *buffer = malloc(BUFFER_SIZE);
    if (!buffer) {
        perror("malloc");
        return 1;
    }
 
    struct io_uring_sqe *sqe = io_uring_get_sqe(&ring);
    if (!sqe) {
        fprintf(stderr, "No space for a new SQE\n");
        return 1;
    }
 
    io_uring_prep_read(sqe, fd, buffer, BUFFER_SIZE, 0);
    io_uring_sqe_set_data(sqe, buffer);
 
    int submit_ret = io_uring_submit(&ring);
    if (submit_ret != 1) {
        fprintf(stderr, "io_uring_submit: %d\n", submit_ret);
        return 1;
    }
 
    struct io_uring_cqe *cqe;
    unsigned head = 0;
    for (;;) {
        io_uring_wait_cqe(&ring, &cqe);
        if (cqe->res != BUFFER_SIZE) {
            fprintf(stderr, "Read failed: %ld\n", cqe->res);
            return 1;
        }
 
        char *buffer = (char *)io_uring_cqe_get_data(cqe);
        printf("Read: %s\n", buffer);
        free(buffer);
 
        io_uring_cq_advance(&ring, head);
        head++;
 
        // 重新提交读取操作
        sqe = io_uring_get_sqe(&ring);
        if (!sqe) {
            fprintf(stderr, "No space for a new SQE\n");
            return 1;
        }
 
        buffer = malloc(BUFFER_SIZE);
        if (!buffer) {
            perror("malloc");
            return 1;
        }
 
        io_uring_prep_read(sqe, fd, buffer, BUFFER_SIZE, 0);
        io_uring_sqe_set_data(sqe, buffer);
 
        submit_ret = io_uring_submit(&ring);
        if (submit_ret != 1) {
            fprintf(stderr, "io_uring_submit: %d\n", submit_ret);
            return 1;
        }
 
        // 退出循环条件：读取到文件末尾或发生错误
        if (cqe->res == 0) {
            break;
        }
    }
 
    close(fd);
    io_uring_queue_exit(&ring)