node-fxplc/dist/esm/async-lock.js

Node.js library for low-level Mitsubishi FX (MELSEC) PLC framed protocol communication

// async-lock.js
// Semplice mutex promise-based per serializzare le operazioni sul transport
// Simple promise-based mutex to serialize protocol frame operations over a transport.
/**
 * Lightweight async lock (FIFO-ish) that chains promises to guarantee mutual exclusion.
 * Usage:
 *   const lock = new AsyncLock();
 *   await lock.run(async () => { /* critical section */ /* });
*/
export class AsyncLock {
    constructor() { this._p = Promise.resolve(); }
    async run(fn) {
        const runPrev = this._p;
        let release;
        this._p = new Promise(r => release = r);
        try {
            await runPrev; // wait previous chain completion
            return await fn();
        }
        finally {
            release();
        }
    }
}