http: add diagnostics channel for http client

Author: theanarkh

doc/api/diagnostics_channel.md

@@ -307,6 +307,108 @@ channel.subscribe(onMessage);
 channel.unsubscribe(onMessage);
 ```
 
+## Example
+
+```mjs
+import http from 'node:http';
+import dc from 'node:diagnostics_channel';
+
+const onClientRequestStart = dc.channel('http.client.request.start');
+const onClientResponseFinish = dc.channel('http.client.response.finish');
+const onServerRequestStart = dc.channel('http.server.request.start');
+const onServerResponseFinish = dc.channel('http.server.response.finish');
+
+onClientRequestStart.subscribe(({ request }) => {
+
+});
+
+onClientResponseFinish.subscribe(({ request, response }) => {
+
+});
+
+onServerRequestStart.subscribe(({
+  request,
+  response,
+  socket,
+  server,
+}) => {
+
+});
+
+onServerResponseFinish.subscribe(({
+  request,
+  response,
+  socket,
+  server,
+}) => {
+
+});
+
+const server = http.createServer((req, res) => {
+  res.end('done');
+});
+
+server.listen(() => {
+  const { port } = server.address();
+  http.get(`http://localhost:${port}`, (res) => {
+    res.resume();
+    res.on('end', () => {
+      server.close();
+    });
+  });
+});
+```
+
+```cjs
+const http = require('http');
+const dc = require('diagnostics_channel');
+
+const onClientRequestStart = dc.channel('http.client.request.start');
+const onClientResponseFinish = dc.channel('http.client.response.finish');
+const onServerRequestStart = dc.channel('http.server.request.start');
+const onServerResponseFinish = dc.channel('http.server.response.finish');
+
+onClientRequestStart.subscribe(({ request }) => {
+
+});
+
+onClientResponseFinish.subscribe(({ request, response }) => {
+
+});
+
+onServerRequestStart.subscribe(({
+  request,
+  response,
+  socket,
+  server,
+}) => {
+
+});
+
+onServerResponseFinish.subscribe(({
+  request,
+  response,
+  socket,
+  server,
+}) => {
+
+});
+
+const server = http.createServer((req, res) => {
+  res.end('done');
+});
+
+server.listen(() => {
+  const { port } = server.address();
+  http.get(`http://localhost:${port}`, (res) => {
+    res.resume();
+    res.on('end', () => {
+      server.close();
+    });
+  });
+});
+```
+
 [`'uncaughtException'`]: process.md#event-uncaughtexception
 [`channel.subscribe(onMessage)`]: #channelsubscribeonmessage
 [`diagnostics_channel.channel(name)`]: #diagnostics_channelchannelname

lib/_http_client.js

@@ -90,6 +90,10 @@ const {
 
 const kClientRequestStatistics = Symbol('ClientRequestStatistics');
 
+const dc = require('diagnostics_channel');
+const onClientRequestStartChannel = dc.channel('http.client.request.start');
+const onClientResponseFinishChannel = dc.channel('http.client.response.finish');
+
 const { addAbortSignal, finished } = require('stream');
 
 let debug = require('internal/util/debuglog').debuglog('http', (fn) => {
@@ -367,6 +371,11 @@ ClientRequest.prototype._finish = function _finish() {
       },
     });
   }
+  if (onClientRequestStartChannel.hasSubscribers) {
+    onClientRequestStartChannel.publish({
+      request: this,
+    });
+  }
 };
 
 ClientRequest.prototype._implicitHeader = function _implicitHeader() {
@@ -645,6 +654,12 @@ function parserOnIncomingClient(res, shouldKeepAlive) {
       },
     });
   }
+  if (onClientResponseFinishChannel.hasSubscribers) {
+    onClientResponseFinishChannel.publish({
+      request: req,
+      response: res,
+    });
+  }
   req.res = res;
   res.req = req;
 

lib/http.js

@@ -123,7 +123,7 @@ module.exports = {
   validateHeaderName,
   validateHeaderValue,
   get,
-  request
+  request,
 };
 
 ObjectDefineProperty(module.exports, 'maxHeaderSize', {

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

@@ -0,0 +1,57 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const http = require('http');
+const dc = require('diagnostics_channel');
+
+const onClientRequestStart = dc.channel('http.client.request.start');
+const onClientResponseFinish = dc.channel('http.client.response.finish');
+const onServerRequestStart = dc.channel('http.server.request.start');
+const onServerResponseFinish = dc.channel('http.server.response.finish');
+
+onClientRequestStart.subscribe(common.mustCall(({ request }) => {
+  assert.strictEqual(typeof request, 'object');
+}));
+
+onClientResponseFinish.subscribe(common.mustCall(({ request, response }) => {
+  assert.strictEqual(typeof request, 'object');
+  assert.strictEqual(typeof response, 'object');
+}));
+
+onServerRequestStart.subscribe(common.mustCall(({
+  request,
+  response,
+  socket,
+  server,
+}) => {
+  assert.strictEqual(typeof request, 'object');
+  assert.strictEqual(typeof response, 'object');
+  assert.strictEqual(typeof socket, 'object');
+  assert.strictEqual(typeof server, 'object');
+}));
+
+onServerResponseFinish.subscribe(common.mustCall(({
+  request,
+  response,
+  socket,
+  server,
+}) => {
+  assert.strictEqual(typeof request, 'object');
+  assert.strictEqual(typeof response, 'object');
+  assert.strictEqual(typeof socket, 'object');
+  assert.strictEqual(typeof server, 'object');
+}));
+
+const server = http.createServer(common.mustCall((req, res) => {
+  res.end('done');
+}));
+
+server.listen(() => {
+  const { port } = server.address();
+  http.get(`http://localhost:${port}`, (res) => {
+    res.resume();
+    res.on('end', () => {
+      server.close();
+    });
+  });
+});