lib: create diagnostics_channel module

PR-URL: https://github.com/nodejs/node/pull/34895
Reviewed-By: Bryan English <bryan@bryanenglish.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Vladimir de Turckheim <vlad2t@hotmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
Reviewed-By: Gabriel Schulhof <gabriel.schulhof@intel.com>
Reviewed-By: Michael Dawson <midawson@redhat.com>

benchmark/diagnostics_channel/publish.js

@@ -0,0 +1,29 @@
+'use strict';
+const common = require('../common.js');
+const dc = require('diagnostics_channel');
+
+const bench = common.createBenchmark(main, {
+  n: [1e8],
+  subscribers: [0, 1, 10],
+});
+
+function noop() {}
+
+function main({ n, subscribers }) {
+  const channel = dc.channel('test');
+  for (let i = 0; i < subscribers; i++) {
+    channel.subscribe(noop);
+  }
+
+  const data = {
+    foo: 'bar'
+  };
+
+  bench.start();
+  for (let i = 0; i < n; i++) {
+    if (channel.hasSubscribers) {
+      channel.publish(data);
+    }
+  }
+  bench.end(n);
+}

benchmark/diagnostics_channel/subscribe.js

@@ -0,0 +1,19 @@
+'use strict';
+const common = require('../common.js');
+const dc = require('diagnostics_channel');
+
+const bench = common.createBenchmark(main, {
+  n: [1e8],
+});
+
+function noop() {}
+
+function main({ n }) {
+  const channel = dc.channel('channel.0');
+
+  bench.start();
+  for (let i = 0; i < n; i++) {
+    channel.subscribe(noop);
+  }
+  bench.end(n);
+}