Question

给出以下代码：

async function (req, res, next) {
  const fd = await fs.open("myfile.txt")
  fs.createReadStream(null, { fd, autoClose: false })
    .on('error', next)
    .on('end', () => fs.close(fd))
    .pipe(res)
}

如果客户端在下载整个文件之前断开连接会怎样？即仍然会调用end或文件描述符泄露，如果是，我该如何解决？如果调用`end'这意味着即使客户端不再侦听整个文件也会被读取？

注意，我知道我可以在没有fd的情况下执行此操作，但这是对更复杂代码的简化。

Answer 1

看起来文件不会被关闭，或者至少不会调用你的end事件处理程序。

您可以为此创建测试，但这是我的：

const http = require('http');
const fs   = require('fs');

var server = http.createServer(function (req, res) {
    console.log('server request received');
    const fd = fs.openSync('myfile.txt', 'r');
    fs.createReadStream(null, { fd, autoClose: false })
        .on('error', err => {
            console.error('file error', err);
        })
        .on('end', () => {
            console.log('file end');
            fs.close(fd);
        })
        .on('close', () => {
            console.log('file closed');
        })
        .pipe(res)
            .on('error', err => console.error('server stream error', err))
            .on('end', () => console.log('server stream end'))
            .on('close', () => console.log('server stream closed'))
    ;
});

server.listen(0, 'localhost', () => {
    const address = server.address();

    var req = http.request({port: address.port}, function (res) {
        res.on('data', data => {
            console.log('response data');
            // Comment next line to read whole file.
            req.abort();
        });
        res.on('end', () => {
            console.log('response ended');
            setTimeout(() => server.close(), 1000);
        });
        req.once('abort', () => {
            console.log('request aborted');
        });
    });

    req.end(() => {
        console.log('request sent');
    });
});

我删除了异步/等待运行测试的简单性。

调用req.abort()时，我得到以下输出：

request sent
server request received
response data
request aborted
response ended
server stream closed

评论该行后，允许代码读取整个文件：

request sent
server request received
response data
response data
response data
response data
response data
response data
file end
response data
response ended

要创建测试myfile.txt，我使用了以下命令：

dd if=/dev/zero of=myfile.txt bs=1k count=200

文件下载和客户端断开连接？

1 个答案: