nstdlib-nightly/lib/internal/perf/event_loop_delay.mjs

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

// Source: https://github.com/nodejs/node/blob/65eff1eb/lib/internal/perf/event_loop_delay.js

import { codes as __codes__ } from "nstdlib/lib/internal/errors";
import { createELDHistogram } from "nstdlib/stub/binding/performance";
import {
  validateInteger,
  validateObject,
} from "nstdlib/lib/internal/validators";
import { Histogram, kHandle, kMap } from "nstdlib/lib/internal/histogram";
import { kEmptyObject } from "nstdlib/lib/internal/util";
import { markTransferMode } from "nstdlib/lib/internal/worker/js_transferable";

const { ERR_ILLEGAL_CONSTRUCTOR, ERR_INVALID_THIS } = __codes__;

const kEnabled = Symbol("kEnabled");

class ELDHistogram extends Histogram {
  constructor(i) {
    throw new ERR_ILLEGAL_CONSTRUCTOR();
  }

  /**
   * @returns {boolean}
   */
  enable() {
    if (this[kEnabled] === undefined)
      throw new ERR_INVALID_THIS("ELDHistogram");
    if (this[kEnabled]) return false;
    this[kEnabled] = true;
    this[kHandle].start();
    return true;
  }

  /**
   * @returns {boolean}
   */
  disable() {
    if (this[kEnabled] === undefined)
      throw new ERR_INVALID_THIS("ELDHistogram");
    if (!this[kEnabled]) return false;
    this[kEnabled] = false;
    this[kHandle].stop();
    return true;
  }
}

/**
 * @param {{
 *   resolution : number
 * }} [options]
 * @returns {ELDHistogram}
 */
function monitorEventLoopDelay(options = kEmptyObject) {
  validateObject(options, "options");

  const { resolution = 10 } = options;
  validateInteger(resolution, "options.resolution", 1);

  return Reflect.construct(
    function () {
      markTransferMode(this, true, false);
      this[kEnabled] = false;
      this[kHandle] = createELDHistogram(resolution);
      this[kMap] = new Map();
    },
    [],
    ELDHistogram,
  );
}

export default monitorEventLoopDelay;