lib: fix diagnostics channel

PR-URL: #44154
Fixes: #44143
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
Reviewed-By: Paolo Insogna <paolo@cowtech.it>
Reviewed-By: Stephen Belanger <admin@stephenbelanger.com>

Author: theanarkh

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

@@ -6,21 +6,18 @@ const dc = require('diagnostics_channel');
 const assert = require('assert');
 const http = require('http');
 
-const incomingStartChannel = dc.channel('http.server.request.start');
-const outgoingFinishChannel = dc.channel('http.server.response.finish');
-
 const als = new AsyncLocalStorage();
 let context;
 
 // Bind requests to an AsyncLocalStorage context
-incomingStartChannel.subscribe(common.mustCall((message) => {
+dc.subscribe('http.server.request.start', common.mustCall((message) => {
   als.enterWith(message);
   context = message;
 }));
 
 // When the request ends, verify the context has been maintained
 // and that the messages contain the expected data
-outgoingFinishChannel.subscribe(common.mustCall((message) => {
+dc.subscribe('http.server.response.finish', common.mustCall((message) => {
   const data = {
     request,
     response,

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

@@ -5,26 +5,24 @@ const http = require('http');
 const net = require('net');
 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');
-
 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;
 
-onClientRequestStart.subscribe(common.mustCall(({ request }) => {
+dc.subscribe('http.client.request.start', common.mustCall(({ request }) => {
   assert.strictEqual(isOutgoingMessage(request), true);
 }));
 
-onClientResponseFinish.subscribe(common.mustCall(({ request, response }) => {
+dc.subscribe('http.client.response.finish', common.mustCall(({
+  request,
+  response
+}) => {
   assert.strictEqual(isOutgoingMessage(request), true);
   assert.strictEqual(isIncomingMessage(response), true);
 }));
 
-onServerRequestStart.subscribe(common.mustCall(({
+dc.subscribe('http.server.request.start', common.mustCall(({
   request,
   response,
   socket,
@@ -36,7 +34,7 @@ onServerRequestStart.subscribe(common.mustCall(({
   assert.strictEqual(isHTTPServer(server), true);
 }));
 
-onServerResponseFinish.subscribe(common.mustCall(({
+dc.subscribe('http.server.response.finish', common.mustCall(({
   request,
   response,
   socket,