Synchronous resize and upload using graphicsmagick - node.js

Question

I am trying to make resizing of a photo and uploading to a server synchronous. I believe the key will be making the stream function synchronous.
function upload(photo, newname, size, cb) {
gm(request(photo))
.resize(size[0], size[1])
.stream(function(err, stdout, stderr) {
var buf = new Buffer('');
stdout.on('data', function(data) {
buf = Buffer.concat([buf, data]);
});
stdout.on('end', function(data) {
var data = {
Bucket: config.s3_bucket_photos,
Key: newname,
Body: buf,
ACL: 'public-read',
ContentType: "image/jpeg"
};
uploadToServerSynchronous(data, cb);
});
});
}

Answer 1

It's not good to do sync operations in NodeJS - it stops processing event queue while Your sync method ends it's work.
As I understand You name "synchronous" things that has callbacks.
How about converting stream to promise?
const downloadAndResizePhotoByUrl = (photoUrl, size) => {
return new Promise((resolve, reject) => {
gm(request(photoUrl))
.resize(size[0], size[1])
.streamFn((error, stdout, stderr) => {
if(error) return reject(error);
let buffer = Buffer.from('');
stdout.on('data', data => {
buffer = Buffer.concat([buffer, data]);
});
stdout.on('end', () => resolve(buffer));
stdout.on('error', error => reject(error));
});
});
}
const uploadPhotoFromUrlToS3 = async (photoUrl, uploadAs, size, cb) => {
try {
const data = await downloadAndResizePhotoByUrl(photoUrl, size);
uploadToServerSynchronous(
{
Bucket: config.s3_bucket_photos,
Key: uploadAs,
Body: Buffer.from(data),
ACL: 'public-read',
ContentType: "image/jpeg"
},
cb
);
}
catch (error) {
cb(error);
}
}