fs-ext/tests/worker-test.js

Extensions to core 'fs' module.

"use strict";

const { Worker, isMainThread, parentPort } = require("node:worker_threads");
const assert = require("node:assert");
const fs = require("node:fs");
const fsExt = require("../fs-ext");

class Mutex {
  constructor(filename) {
    this.filename = filename;
  }
  lock() {
    this.fd = fs.openSync(this.filename, "w+");
    fsExt.flockSync(this.fd, "ex");
  }
  unlock() {
    fsExt.flockSync(this.fd, "un");
    fs.closeSync(this.fd);
    fs.rmSync(this.filename, { force: true });
    this.fd = null;
  }
}

const m = new Mutex("worker-test.lock");
const write = function (msg) {
  fs.appendFileSync("worker-test.log", `${msg}\n`, { flags: "as" });
}

fs.rmSync("worker-test.log", { force: true });

if (isMainThread) {
  m.lock();
  setTimeout(() => {
    write("releasing main lock");
    m.unlock();
  }, 100);
  const worker = new Worker(__filename);
  worker.on("message", () => {
    assert.deepEqual(
      fs
        .readFileSync("worker-test.log", "utf-8")
        .split("\n")
        .map((line) => line.trim())
        .filter((a) => a),
      ["releasing main lock", "worker lock acquired"]
    );
    worker.terminate();
    fs.rmSync("worker-test.log");
  });
}
else {
  m.lock();
  write("worker lock acquired");
  m.unlock();
  parentPort.postMessage("complete");
}