All files / lib/internal/perf event_loop_delay.js

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'use strict';
const {
  ReflectConstruct,
  SafeMap,
  Symbol,
} = primordials;
 
const {
  codes: {
    ERR_ILLEGAL_CONSTRUCTOR,
    ERR_INVALID_THIS,
  }
} = require('internal/errors');
 
const {
  createELDHistogram,
} = internalBinding('performance');
 
const {
  validateInteger,
  validateObject,
} = require('internal/validators');
 
const {
  Histogram,
  kHandle,
  kMap,
} = require('internal/histogram');
 
const {
  makeTransferable,
} = require('internal/worker/js_transferable');
 
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 = {}) {
  validateObject(options, 'options');
 
  const { resolution = 10 } = options;
  validateInteger(resolution, 'options.resolution', 1);
 
  return makeTransferable(ReflectConstruct(
    function() {
      this[kEnabled] = false;
      this[kHandle] = createELDHistogram(resolution);
      this[kMap] = new SafeMap();
    }, [], ELDHistogram));
}
 
module.exports = monitorEventLoopDelay;