nope/lib/profiling/index.nodejs.ts

"use strict";
const fs = require("fs");
const v8Profiler = require("v8-profiler-next");

import { join } from "path";
import { replaceAll } from "../helpers/stringMethods";
import { getNopeLogger } from "../index.browser";
import { createFile } from "../index.nodejs";

export const CURRENT_DATE = _parsableISOString();
export const DEFAULT_LOG_LOCATION = join(process.cwd(), "logs");
const DEFAULT_FILE = join(
  DEFAULT_LOG_LOCATION,
  "cpu_profile_" + CURRENT_DATE + ".cpuprofile"
);
const logger = getNopeLogger("CPU-Profiler");

function _parsableISOString(date = new Date()) {
  let isoString = date.toISOString();
  isoString = replaceAll(isoString, ":", "-");
  isoString = replaceAll(isoString, ".", "-");
  return isoString;
}

/**
 * Generates a Log-File Path based on the given name with the following format:
 * /logs/{name}_{date}.log
 *
 * @export
 * @param {string} name Name of the File.
 * @return {string}
 * @backend **Only in Nodejs available**
 */
export function generateLogfilePath(name: string): string {
  return join(
    DEFAULT_LOG_LOCATION,
    name + "_" + _parsableISOString() + ".cpuprofile"
  );
}

export function recordCPUProfile(pathToFile = DEFAULT_FILE) {
  const title = "cpu-profile";

  // set generateType 1 to generate new format for cpuprofile
  // to be compatible with cpuprofile parsing in vscode.
  v8Profiler.setGenerateType(1);

  // ex. 5 mins cpu profile
  v8Profiler.startProfiling(title, true);

  let stopped = false;

  const stopProfiling = async () => {
    if (stopped) {
      return;
    }

    stopped = true;

    const profile = v8Profiler.stopProfiling(title);

    const promise = new Promise((resolve, reject) => {
      profile.export(function (error, result) {
        if (error) {
          reject(error);
        }
        resolve(result);
      });
    });

    const result: any = await promise;

    // if it doesn't have the extension .cpuprofile then
    // chrome's profiler tool won't like it.

    // examine the profile:
    //   Navigate to chrome://inspect
    //   Click Open dedicated DevTools for Node
    //   Select the profiler tab
    //   Load your file
    await createFile(pathToFile, result);

    logger.info(
      "Please open google chrome and open chrome://inspect and load the file",
      pathToFile
    );

    // Clear the Profile.
    profile.delete();
  };

  return stopProfiling;
}