http: add diagnostics channel http.client.request.error

PR-URL: #54054
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Marco Ippolito <marcoippolito54@gmail.com>
Reviewed-By: Ethan Arrowood <ethan@arrowood.dev>

doc/api/diagnostics_channel.md

@@ -1119,6 +1119,13 @@ independently.
 
 Emitted when client starts a request.
 
+`http.client.request.error`
+
+* `request` {http.ClientRequest}
+* `error` {Error}
+
+Emitted when an error occurs during a client request.
+
 `http.client.response.finish`
 
 * `request` {http.ClientRequest}

lib/_http_client.js

@@ -95,8 +95,19 @@ const kClientRequestStatistics = Symbol('ClientRequestStatistics');
 
 const dc = require('diagnostics_channel');
 const onClientRequestStartChannel = dc.channel('http.client.request.start');
+const onClientRequestErrorChannel = dc.channel('http.client.request.error');
 const onClientResponseFinishChannel = dc.channel('http.client.response.finish');
 
+function emitErrorEvent(request, error) {
+ if (onClientRequestErrorChannel.hasSubscribers) {
+ onClientRequestErrorChannel.publish({
+ request,
+ error,
+ });
+ }
+ request.emit('error', error);
+}
+
 const { addAbortSignal, finished } = require('stream');
 
 let debug = require('internal/util/debuglog').debuglog('http', (fn) => {
@@ -348,7 +359,7 @@ function ClientRequest(input, options, cb) {
  if (typeof opts.createConnection === 'function') {
  const oncreate = once((err, socket) => {
  if (err) {
- process.nextTick(() => this.emit('error', err));
+ process.nextTick(() => emitErrorEvent(this, err));
  } else {
  this.onSocket(socket);
  }
@@ -470,7 +481,7 @@ function socketCloseListener() {
  // receive a response. The error needs to
  // fire on the request.
  req.socket._hadError = true;
- req.emit('error', new ConnResetException('socket hang up'));
+ emitErrorEvent(req, new ConnResetException('socket hang up'));
  }
  req._closed = true;
  req.emit('close');
@@ -497,7 +508,7 @@ function socketErrorListener(err) {
  // For Safety. Some additional errors might fire later on
  // and we need to make sure we don't double-fire the error event.
  req.socket._hadError = true;
- req.emit('error', err);
+ emitErrorEvent(req, err);
  }
 
  const parser = socket.parser;
@@ -521,7 +532,7 @@ function socketOnEnd() {
  // If we don't have a response then we know that the socket
  // ended prematurely and we need to emit an error on the request.
  req.socket._hadError = true;
- req.emit('error', new ConnResetException('socket hang up'));
+ emitErrorEvent(req, new ConnResetException('socket hang up'));
  }
  if (parser) {
  parser.finish();
@@ -546,7 +557,7 @@ function socketOnData(d) {
  socket.removeListener('end', socketOnEnd);
  socket.destroy();
  req.socket._hadError = true;
- req.emit('error', ret);
+ emitErrorEvent(req, ret);
  } else if (parser.incoming && parser.incoming.upgrade) {
  // Upgrade (if status code 101) or CONNECT
  const bytesParsed = ret;
@@ -877,7 +888,7 @@ function onSocketNT(req, socket, err) {
  err = new ConnResetException('socket hang up');
  }
  if (err) {
- req.emit('error', err);
+ emitErrorEvent(req, err);
  }
  req._closed = true;
  req.emit('close');

test/parallel/test-diagnostics-channel-http.js

@@ -1,5 +1,6 @@
 'use strict';
 const common = require('../common');
+const { addresses } = require('../common/internet');
 const assert = require('assert');
 const http = require('http');
 const net = require('net');
@@ -9,9 +10,15 @@ const isHTTPServer = (server) => server instanceof http.Server;
 const isIncomingMessage = (object) => object instanceof http.IncomingMessage;
 const isOutgoingMessage = (object) => object instanceof http.OutgoingMessage;
 const isNetSocket = (socket) => socket instanceof net.Socket;
+const isError = (error) => error instanceof Error;
 
 dc.subscribe('http.client.request.start', common.mustCall(({ request }) => {
  assert.strictEqual(isOutgoingMessage(request), true);
+}, 2));
+
+dc.subscribe('http.client.request.error', common.mustCall(({ request, error }) => {
+ assert.strictEqual(isOutgoingMessage(request), true);
+ assert.strictEqual(isError(error), true);
 }));
 
 dc.subscribe('http.client.response.finish', common.mustCall(({
@@ -50,8 +57,14 @@ const server = http.createServer(common.mustCall((req, res) => {
  res.end('done');
 }));
 
-server.listen(() => {
+server.listen(async () => {
  const { port } = server.address();
+ const invalidRequest = http.get({
+ host: addresses.INVALID_HOST,
+ });
+ await new Promise((resolve) => {
+ invalidRequest.on('error', resolve);
+ });
  http.get(`http://localhost:${port}`, (res) => {
  res.resume();
  res.on('end', () => {