call-once-promise

Why use call-once-promise? When initializing systems (e.g. database connect, config read), multiple parallel requests can trigger duplicate connection routines. They need to run once, share the promise, and retry if they fail.

A wrapper that ensures an async function runs exactly once, sharing the active promise across all callers and resetting upon failure to allow retries.

⚡ Features

• Guarantees single execution for async functions
• Caches active promise and resolves all concurrent callers
• Resets on failure so subsequent attempts can retry

📦 Installation

npm i call-once-promise

🚀 Usage

import { oncePromise } from 'call-once-promise';

let calls = 0;
const connectDb = oncePromise(async () => {
  calls++;
  console.log('Connecting to database...');
  return 'ConnectionPool';
});

// Call simultaneously
const [c1, c2, c3] = await Promise.all([connectDb(), connectDb(), connectDb()]);
console.log('Calls executed:', calls); // 1

⚙️ API Reference

oncePromise(fn)

• fn: () => Promise<T> - Target async initializer.
• Returns a guarded function resolving a shared Promise<T>.

📺 Demonstration

📄 License

MIT License.