src: add trace points to dns

Add trace points to dns under node.dns.native category.
Emit trace events for dns operations. Use the
nestable async events instead of deprecated ones.
Include test code to verify the trace log. The
trace name is stored as const char* class variable.
The test code is to check each operation in separate
sync processes.

Refs: https://github.com/nodejs/node/pull/19157

PR-URL: https://github.com/nodejs/node/pull/21840
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Gireesh Punathil <gpunathi@in.ibm.com>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>

1 files changed, 68 insertions, 0 deletions

diff --git a/test/internet/test-trace-events-dns.js b/test/internet/test-trace-events-dns.js
new file mode 100644
index 0000000000..3eb787a2ca
--- /dev/null
+++ b/test/internet/test-trace-events-dns.js
@@ -0,0 +1,68 @@
+'use strict';
+const common = require('../common');
+const assert = require('assert');
+const cp = require('child_process');
+const path = require('path');
+const tmpdir = require('../common/tmpdir');
+const fs = require('fs');
+const util = require('util');
+
+if (!common.isMainThread)
+  common.skip('process.chdir is not available in Workers');
+
+const traceFile = 'node_trace.1.log';
+
+tmpdir.refresh();
+process.chdir(tmpdir.path);
+
+const test_str = 'const dns = require("dns");' +
+'const options = {' +
+'  family: 4,' +
+'  hints: dns.ADDRCONFIG | dns.V4MAPPED,' +
+'};';
+
+const tests = {
+  'lookup': 'dns.lookup("example.com", options, (err, address, family) => {});',
+  'lookupService': 'dns.lookupService("127.0.0.1", 22, ' +
+                   '(err, hostname, service) => {});',
+  'reverse': 'dns.reverse("8.8.8.8", (err, hostnames) => {});',
+  'resolveAny': 'dns.resolveAny("example.com", (err, res) => {});',
+  'resolve4': 'dns.resolve4("example.com", (err, res) => {});',
+  'resolve6': 'dns.resolve6("example.com", (err, res) => {});',
+  'resolveCname': 'dns.resolveCname("example.com", (err, res) => {});',
+  'resolveMx': 'dns.resolveMx("example.com", (err, res) => {});',
+  'resolveNs': 'dns.resolveNs("example.com", (err, res) => {});',
+  'resolveTxt': 'dns.resolveTxt("example.com", (err, res) => {});',
+  'resolveSrv': 'dns.resolveSrv("example.com", (err, res) => {});',
+  'resolvePtr': 'dns.resolvePtr("example.com", (err, res) => {});',
+  'resolveNaptr': 'dns.resolveNaptr("example.com", (err, res) => {});',
+  'resolveSoa': 'dns.resolveSoa("example.com", (err, res) => {});'
+};
+
+for (const tr in tests) {
+  const proc = cp.spawnSync(process.execPath,
+                            [ '--trace-event-categories',
+                              'node.dns.native',
+                              '-e',
+                              test_str + tests[tr]
+                            ],
+                            { encoding: 'utf8' });
+
+  // Make sure the operation is successful.
+  assert.strictEqual(proc.status, 0, `${tr}:\n${util.inspect(proc)}`);
+
+  const file = path.join(tmpdir.path, traceFile);
+
+  // Confirm that trace log file is created.
+  assert(common.fileExists(file));
+  const data = fs.readFileSync(file);
+  const traces = JSON.parse(data.toString()).traceEvents
+        .filter((trace) => trace.cat !== '__metadata');
+
+  assert(traces.length > 0);
+
+  // DNS native trace events should be generated.
+  assert(traces.some((trace) => {
+    return (trace.name === tr && trace.pid === proc.pid);
+  }));
+}