server hangs if a handler returns undefined

[danielroe]

with automatic promisifying, if a handler returns undefined, the promise never resolves and the server hangs...

Is there a reason we don't immediately resolve(undefined) if the handler does?

[pi0]

Nice catch, but something i'm afraid that, is we would continue to next middleware if handle uses an async (callback based) operation like this:

export default (req, res) {
  db.getUser((user) => {
     res.end(JSON.stringify(user))
  })
}

A legacy middleware like this would be broken.... I was supposing middleware (or better handle since has only two params) should always end request and so we listen to res.end. Do you have a case that it causes server to hang-up?

[danielroe]

Very good point....! Will remove from #10

Yes, I like the simplicity of writing a handler like:

app.use('/api', (req) => {
  if (req.method !== 'GET') return

  return data
})

... but it's more important not to break promise-based handlers.

[pi0]

I see... In that case we can introduce something like { legacy: true } and use modern syntax by default. Wdyt?

[danielroe]

I would really like that, but do we lose the benefit of interop with express middleware where the user doesn't have control over each use() call? Could we create an entire App instance with { legacy: true } and have that behaviour apply to every handler...?

[danielroe]

For a repro of hang:

1. Clone https://github.com/danielroe/jiti-h2-tests
2. yarn && yarn dev
3. curl http://localhost:3000/api/js/csr - (using h2) hangs
4. curl http://localhost:3000/api/ts/csr - (using express) succeeds (e.g. falls back to Nuxt 404)

Was trying (and failed) to replicate issue with #13 - but oh well, at least they add a few more tests 🤷‍♂️

[pi0]

Thanks for repro @danielroe! Actually it helped to find two issues:

• When using h2 as a sub-app, we should use req.url not originalUrl to allow using relative paths (no /api/js in middleware itself)
• Since connect detects app.handle, the hanging issue was happening so i made it hidden under app._handle (src)