libuv 同时读写文件

// libuv实现边写边读
#include <stdio.h>
#include <spdlog/spdlog.h>
#include <uv.h>

typedef struct {
    char buffer[1024];
    uv_buf_t buf;
    uv_fs_t open_read_fs;
    uv_fs_t open_write_fs;

    uv_fs_t read_fs;
    uv_fs_t write_fs;
    size_t  offset = 0;
} read2write_t;


void on_write_cb(uv_fs_t* req);

void on_read_cb(uv_fs_t* req){
    spdlog::info("read:{}", req->result);
    auto data = (read2write_t *)req->data;
    uv_fs_req_cleanup(req);
    if (req->result < 0){
        spdlog::error("read error");
    }
    else if (req->result == 0){
        uv_fs_close(uv_default_loop(), &data->open_read_fs, data->open_read_fs.result, nullptr);
        uv_fs_close(uv_default_loop(), &data->open_write_fs, data->open_write_fs.result, nullptr);
    }
    else{
        data->write_fs.data = data;
        data->buf = uv_buf_init(data->buffer, req->result);
        int offset = data->offset;
        data->offset += req->result;
        uv_fs_write(uv_default_loop(), &data->write_fs, data->open_write_fs.result, &data->buf, 1, offset, on_write_cb);
    }

}

void on_write_cb(uv_fs_t* req){
    auto data = (read2write_t *)req->data;
    uv_fs_req_cleanup(req);
    if (req->result < 0){
        spdlog::error("write error");
    }
    else{
        data->read_fs.data = data;
        uv_fs_read(uv_default_loop(), &data->read_fs, data->open_read_fs.result, &data->buf, 1, data->offset, on_read_cb);
    }

}


void on_open_write_cb(uv_fs_t* req){  
    if (req->result < 0){
        spdlog::error("write open file error:{}", uv_strerror(req->result));
    }else {
        auto data = (read2write_t*) req->data;
        data->buf = uv_buf_init(data->buffer, sizeof(data->buffer));
        data->read_fs.data = data;
        uv_fs_read(uv_default_loop(), &data->read_fs, data->open_read_fs.result, &data->buf, 1, 0, on_read_cb);
    }
}

void on_open_read_cb(uv_fs_t* req){  
    if (req->result < 0){
        spdlog::error("read open file error:{}", uv_strerror(req->result));
    }else{
        auto data = (read2write_t*) req->data;
        data->open_write_fs.data = data;
        uv_fs_open(uv_default_loop(), &data->open_write_fs,  "./test_write.txt",  O_CREAT | O_WRONLY, 0,  on_open_write_cb);
    }
}

int main(){
    read2write_t context;
    context.open_read_fs.data = (void*)&context;
    uv_fs_open(uv_default_loop(), &context.open_read_fs,  "./test.txt",  O_RDONLY, 0,  on_open_read_cb);
    return uv_run(uv_default_loop(), UV_RUN_DEFAULT);
}