linux 异步io 回调

#include <aio.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

void aio_completion_handler(sigval_t sigval) {
    struct aiocb *req;
    req = (struct aiocb *)sigval.sival_ptr;
    if (aio_error(req) == 0) {
        printf("Read %ld bytes\n", aio_return(req));
    } else {
        perror("aio_error");
    }
}

int main() {
    int fd = open("testfile.txt", O_RDONLY);
    if (fd == -1) {
        perror("open");
        return 1;
    }

    struct aiocb aio_req;
    memset(&aio_req, 0, sizeof(struct aiocb));
    aio_req.aio_fildes = fd;
    aio_req.aio_buf = malloc(1024);
    aio_req.aio_nbytes = 1024;
    aio_req.aio_offset = 0;
    aio_req.aio_sigevent.sigev_notify = SIGEV_THREAD;
    aio_req.aio_sigevent.sigev_notify_function = aio_completion_handler;
    aio_req.aio_sigevent.sigev_value.sival_ptr = &aio_req;

    if (aio_read(&aio_req) == -1) {
        perror("aio_read");
        close(fd);
        free(aio_req.aio_buf);
        return 1;
    }

    // Do other work here...

    // Wait for the I/O operation to complete
    while (aio_error(&aio_req) == EINPROGRESS) {
        usleep(100);
    }

    close(fd);
    free(aio_req.aio_buf);
    return 0;
}