perf: handling backpressure without timer

[cesco69]

From https://github.com/uNetworking/uWebSockets.js/releases/tag/v20.64.0

Bumps uWS to v20.77.0 with important backpressure fix (see main repo for explanation)

Tested with

const express = require('../src/index.js');
const compression = require('compression');
const app = express();

// force encoding by query param ?compress=
app.use((req, res, next) => {
  const enc = req.query.compress;
  if (enc) {
    req.headers['accept-encoding'] = enc;
  }
  next();
});

app.use(compression({ threshold: 1 }));
app.use(express.static('tests/parts'));

const PORT = 13335;
app.listen(PORT, () => {
  const base = `http://localhost:${PORT}`;
  const files = ['small-file.json', 'medium-file.json', 'large-file.json'];
  const encodings = ['gzip', 'br', 'deflate'];

  console.log(`\n  Server on ${base}\n`);
  console.log('  === Links ===\n');

  for (const file of files) {
    console.log(`  ${file}`);
    console.log(`     ${'identity'.padEnd(8)} : ${base}/${file}?compress=identity`);
    for (const enc of encodings) {
      console.log(`     ${enc.padEnd(8)} : ${base}/${file}?compress=${enc}`);
    }
    console.log();
  }
});

Works on Chrome/Windows with gzip, br and deflate

Ref uNetworking/uWebSockets.js#1249

[cesco69]

@GetThatCookie take a look

[GetThatCookie]

From my side this looks like the right minimal step.

It removes the timer / batching workaround from the chunked streaming path and goes back to direct res.write(chunk) with onWritable(...), which is leaner and much more in line with the current uWS backpressure model after uNetworking/uWebSockets.js#1249.

If a real HTTP tryWrite lands upstream later, ultimate-express could move to that.
See uNetworking/uWebSockets#1922.

But I would not block this PR on it.