[style] use async/await

[dannycoates]

It might be fun to use async/await syntax on the server.

Here's a sample snippet:

app.get('/download/:id', async (req, res) => {
  const id = req.params.id;
  if (!validateID(id)) {
    return res.sendStatus(404);
  }
  try {
    const filename = await storage.filename(id);
    const contentLength = await storage.length(id);
    const timeToExpiry = await storage.ttl(id);
    res.render('download', {
      filename: decodeURIComponent(filename),
      filesize: bytes(contentLength),
      sizeInBytes: contentLength,
      timeToExpiry: timeToExpiry
    });
  } catch (e) {
    res.status(404).render('notfound');
  }
});

[pdehaan]

💯

Related, doing something like #64 to convert Redis calls to a promise style instead of callback style, would make it play much better w/ async/await.
As would switching to the already promise-based fetch() API, circa #32 (although that's more of a front end optimization).

[weihanglo]

I changed all promises into async functions in express at weihanglo/send@bbe111a.

However, in storage.js, methods on Redis client seem cannot be promisified by NodeJS 8 util.promisify. I thought this issue may be related to 424eb2c. Any idea?

[dannycoates]

@weihanglo thanks! Feel free to submit a PR and we can discuss the details there.

[pdehaan]

Awesome work, @weihanglo!

There are a few more Promise notes buried in #64 (most notably the #64 (comment) which has a pointer to the official Redis+Promise documentation on using bluebird to promisify the entire RedisClient using something like:

bluebird.promisifyAll(redis.RedisClient.prototype);

I only briefly played with their sample code, but I'm sure we could figure it out if you need a second pair of eyes.

[gautamkrishnar]

@pdehaan Can this issue be closed? I think it's fixed now...

[pdehaan]

@gautamkrishnar I think we're still keeping this open until we try and promisify the server/storage.js bits.