proper-lockfile

import { lock, unlock } from 'proper-lockfile'; import { promises as fs } from 'fs'; import path from 'path'; const filePath = path.join(process.cwd(), 'my-resource.txt'); const lockFileOptions = { stale: 15000, // Consider lock stale after 15 seconds update: 5000, // Update mtime every 5 seconds retries: { retries: 5, factor: 2, minTimeout: 1000, maxTimeout: 10000, randomize: true, }, onCompromised: (err) => { console.error('Lock was compromised:', err.message); // Implement critical error handling here, e.g., exit process process.exit(1); }, }; async function accessResourceWithLock() { let release; try { // Ensure the target file exists before trying to lock it await fs.writeFile(filePath, 'Initial content.', { flag: 'a+' }); console.log('Attempting to acquire lock...'); release = await lock(filePath, lockFileOptions); console.log('Lock acquired. Performing sensitive operation...'); // Simulate work await new Promise(resolve => setTimeout(resolve, Math.random() * 3000 + 1000)); await fs.appendFile(filePath, `\nAccessed at ${new Date().toISOString()} by process ${process.pid}`); console.log('Sensitive operation complete. Releasing lock...'); } catch (error) { console.error('Failed to acquire or release lock:', error.message); if (error.code === 'ELOCKED') { console.warn('File is already locked by another process.'); } } finally { if (release) { try { await release(); console.log('Lock released successfully.'); } catch (error) { console.error('Error releasing lock:', error.message); } } else { // If lock was never acquired, or release failed (e.g. compromised), ensure cleanup. // In a real scenario, you might also attempt `unlock(filePath)` here if `release` failed // but only if you are confident it's safe to force-unlock. console.log('No release function available or lock acquisition failed. No explicit release needed/possible.'); } } } accessResourceWithLock();