node/test/pummel/test-net-throttle.js

'use strict';
const common = require('../common');
const assert = require('assert');
const net = require('net');

const N = 1024 * 1024;
const part_N = N / 3;
let chars_recved = 0;
let npauses = 0;

console.log('build big string');
const body = 'C'.repeat(N);

console.log(`start server on port ${common.PORT}`);

const server = net.createServer(function(connection) {
  connection.write(body.slice(0, part_N));
  connection.write(body.slice(part_N, 2 * part_N));
  assert.strictEqual(false, connection.write(body.slice(2 * part_N, N)));
  console.log(`bufferSize: ${connection.bufferSize}`, 'expecting', N);
  assert.ok(0 <= connection.bufferSize &&
            connection._writableState.length <= N);
  connection.end();
});

server.listen(common.PORT, function() {
  let paused = false;
  const client = net.createConnection(common.PORT);
  client.setEncoding('ascii');
  client.on('data', function(d) {
    chars_recved += d.length;
    console.log(`got ${chars_recved}`);
    if (!paused) {
      client.pause();
      npauses += 1;
      paused = true;
      console.log('pause');
      const x = chars_recved;
      setTimeout(function() {
        assert.strictEqual(chars_recved, x);
        client.resume();
        console.log('resume');
        paused = false;
      }, 100);
    }
  });

  client.on('end', function() {
    server.close();
    client.end();
  });
});


process.on('exit', function() {
  assert.strictEqual(N, chars_recved);
  assert.strictEqual(true, npauses > 2);
});