nstdlib-nightly/lib/trace_events.mjs

Node.js standard library converted to runtime-agnostic ES modules.

// Source: https://github.com/nodejs/node/blob/65eff1eb/lib/trace_events.js

import { hasTracing } from "nstdlib/stub/binding/config";
import { codes as __codes__ } from "nstdlib/lib/internal/errors";
import { ownsProcessState } from "nstdlib/lib/internal/worker";
import {
  CategorySet,
  getEnabledCategories,
} from "nstdlib/stub/binding/trace_events";
import { customInspectSymbol } from "nstdlib/lib/internal/util";
import { format } from "nstdlib/lib/internal/util/inspect";
import {
  validateObject,
  validateStringArray,
} from "nstdlib/lib/internal/validators";

const kMaxTracingCount = 10;

const { ERR_TRACE_EVENTS_CATEGORY_REQUIRED, ERR_TRACE_EVENTS_UNAVAILABLE } =
  __codes__;

if (!hasTracing || !ownsProcessState) throw new ERR_TRACE_EVENTS_UNAVAILABLE();

const enabledTracingObjects = new Set();

class Tracing {
  #handle;
  #categories;
  #enabled = false;

  constructor(categories) {
    this.#handle = new CategorySet(categories);
    this.#categories = categories;
  }

  enable() {
    if (!this.#enabled) {
      this.#enabled = true;
      this.#handle.enable();
      enabledTracingObjects.add(this);
      if (enabledTracingObjects.size > kMaxTracingCount) {
        process.emitWarning(
          "Possible trace_events memory leak detected. There are more than " +
            `${kMaxTracingCount} enabled Tracing objects.`,
        );
      }
    }
  }

  disable() {
    if (this.#enabled) {
      this.#enabled = false;
      this.#handle.disable();
      enabledTracingObjects.delete(this);
    }
  }

  get enabled() {
    return this.#enabled;
  }

  get categories() {
    return Array.prototype.join.call(this.#categories, ",");
  }

  [customInspectSymbol](depth, opts) {
    if (typeof depth === "number" && depth < 0) return this;

    const obj = {
      enabled: this.enabled,
      categories: this.categories,
    };
    return `Tracing ${format(obj)}`;
  }
}

function createTracing(options) {
  validateObject(options, "options");
  validateStringArray(options.categories, "options.categories");

  if (options.categories.length <= 0)
    throw new ERR_TRACE_EVENTS_CATEGORY_REQUIRED();

  return new Tracing(options.categories);
}

export { createTracing };
export { getEnabledCategories };