trace_events: use private fields instead of symbols for Tracing

PR-URL: #51180
Refs: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Classes/Private_properties
Reviewed-By: James M Snell <[email protected]>
Reviewed-By: Luigi Pinca <[email protected]>
Reviewed-By: Trivikram Kamat <[email protected]>
Reviewed-By: Yagiz Nizipli <[email protected]>

Author: Jungku Lee

lib/trace_events.js

@@ -3,13 +3,9 @@
 const {
   ArrayPrototypeJoin,
   SafeSet,
-  Symbol,
 } = primordials;
 
 const { hasTracing } = internalBinding('config');
-const kHandle = Symbol('handle');
-const kEnabled = Symbol('enabled');
-const kCategories = Symbol('categories');
 
 const kMaxTracingCount = 10;
 
@@ -33,16 +29,19 @@ const {
 const enabledTracingObjects = new SafeSet();
 
 class Tracing {
+  #handle;
+  #categories;
+  #enabled = false;
+
   constructor(categories) {
-    this[kHandle] = new CategorySet(categories);
-    this[kCategories] = categories;
-    this[kEnabled] = false;
+    this.#handle = new CategorySet(categories);
+    this.#categories = categories;
   }
 
   enable() {
-    if (!this[kEnabled]) {
-      this[kEnabled] = true;
-      this[kHandle].enable();
+    if (!this.#enabled) {
+      this.#enabled = true;
+      this.#handle.enable();
       enabledTracingObjects.add(this);
       if (enabledTracingObjects.size > kMaxTracingCount) {
         process.emitWarning(
@@ -54,19 +53,19 @@ class Tracing {
   }
 
   disable() {
-    if (this[kEnabled]) {
-      this[kEnabled] = false;
-      this[kHandle].disable();
+    if (this.#enabled) {
+      this.#enabled = false;
+      this.#handle.disable();
       enabledTracingObjects.delete(this);
     }
   }
 
   get enabled() {
-    return this[kEnabled];
+    return this.#enabled;
   }
 
   get categories() {
-    return ArrayPrototypeJoin(this[kCategories], ',');
+    return ArrayPrototypeJoin(this.#categories, ',');
   }
 
   [customInspectSymbol](depth, opts) {

test/parallel/test-util-inspect.js

@@ -2920,7 +2920,7 @@ assert.strictEqual(
   try {
     const trace = require('trace_events').createTracing({ categories: ['fo'] });
     const actualDepth0 = util.inspect({ trace }, { depth: 0 });
-    assert.strictEqual(actualDepth0, '{ trace: [Tracing] }');
+    assert.strictEqual(actualDepth0, '{ trace: Tracing {} }');
     const actualDepth1 = util.inspect({ trace }, { depth: 1 });
     assert.strictEqual(
       actualDepth1,