Acquire a lock across processes using the file system

fileLock.js

const fs = require("fs");

const acquireLock = async (identifier, retries = 5, delay = 1000) => {
  const pathname = `${identifier}.lock`;
  const acquire = () => {
    try {
      fs.mkdirSync(pathname);
      return true;
    } catch {}
  };
  const release = () => fs.rmdirSync(pathname);
  for (let i = 0; i < retries; i++) {
    if (acquire()) return release;
    await new Promise((r) => setTimeout(r, delay));
  }
};

usage.js

const usage = async () => {
  const lock = await acquireLock("asdf");
  if (lock) {
    console.log("got the lock!");
    lock();
  } else {
    console.log("failed to get the lock!");
  }
};

usage();