use events to wire upload tracking instead of racing with setImmediate

source/request-as-event-emitter.js

@@ -103,13 +103,11 @@ module.exports = (options = {}) => {
  return;
  }
 
- setImmediate(() => {
- try {
- getResponse(response, options, emitter, redirects);
- } catch (error) {
- emitter.emit('error', error);
- }
- });
+ try {
+ getResponse(response, options, emitter, redirects);
+ } catch (error) {
+ emitter.emit('error', error);
+ }
  });
 
  cacheReq.on('error', error => {
@@ -122,7 +120,7 @@ module.exports = (options = {}) => {
 
  cacheReq.once('request', req => {
  let aborted = false;
- req.once('abort', _ => {
+ req.once('abort', () => {
  aborted = true;
  });
 
@@ -148,8 +146,7 @@ module.exports = (options = {}) => {
  total: uploadBodySize
  });
 
- const socket = req.connection;
- if (socket) {
+ req.once('socket', socket => {
  const onSocketConnect = () => {
  const uploadEventFrequency = 150;
 
@@ -183,26 +180,22 @@ module.exports = (options = {}) => {
  }, uploadEventFrequency);
  };
 
- // Only subscribe to `connect` event if we're actually connecting a new
- // socket, otherwise if we're already connected (because this is a
- // keep-alive connection) do not bother. This is important since we won't
- // get a `connect` event for an already connected socket.
  if (socket.connecting) {
  socket.once('connect', onSocketConnect);
  } else {
+ // The socket is being reused from pool,
+ // so the connect event will not be emitted
  onSocketConnect();
  }
- }
+ });
  });
 
  if (options.gotTimeout) {
  clearInterval(progressInterval);
  timedOut(req, options.gotTimeout);
  }
 
- setImmediate(() => {
- emitter.emit('request', req);
- });
+ emitter.emit('request', req);
  });
  };