wait for all streams to finish - stream a directory of files

Question

I'm using client.upload in pkgcloud to upload a directory of files. How can I execute a callback after all the streams have finished? Is there a built-in way to register each stream's "finish" event and execute a callback after they have all fired?

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

One way to do it, is to generate a Promise task for each upload, then utilizing Promise.all().

Assuming you are using ES6, then the code would look something like this:

    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.'); });

Alternatively, if you have access to async / await - you can utilize this. For example:

    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.');