等待所有流完成 - 流式传输文件目录

Question

我使用client.upload在pkgcloud上传文件的目录.所有流完成后执行回调的最佳方法是什么？是否有一种内置方式来注册每个流的"完成"事件并在它们全部被触发后执行回调？

var filesToUpload = fs.readdirSync("./local_path"); // will make this async

for(let file of filesToUpload) {
    var writeStream = client.upload({
        container: "mycontainer,
        remote: file
    });
    // seems like i should register finish events with something
    writeStream.on("finish", registerThisWithSomething);
    fs.createReadStream("./local_path/" + file).pipe(writeStream);
}

Answer 1

一种方法是Promise为每次上传生成一个任务,然后使用Promise.all().

假设您使用的是ES6,代码看起来像这样:

const uploadTasks = filesToUpload.map((file) => new Promise((resolve, reject) => {
    var writeStream = client.upload({
        container: "mycontainer,
        remote: file
    });
    // seems like i should register finish events with something
    writeStream.on("finish", resolve);
    fs.createReadStream("./local_path/" + file).pipe(writeStream);
});

Promise.all(uploadTasks)
  .then(() => { console.log('All uploads completed.'); });

或者,如果您有权访问async / await- 您可以使用它.例如:

const uploadFile = (file) => new Promise((resolve, reject) => {
  const writeStream = client.upload({
    container: "mycontainer,
    remote: file
  });
  writeStream.on("finish", resolve);
  fs.createReadStream("./local_path/" + file).pipe(writeStream);
}

const uploadFiles = async (files) => {
  for(let file of files) {
    await uploadFile(file);
  }
}

await uploadFiles(filesToUpload);
console.log('All uploads completed.');