This project serves as a demo to showcase the usage of Copy-on-write (CoW) capabilities within new Windows 11 Development drives. It's built using a combination of C++ for the native operations and Node.js for the JavaScript interface.

Note: I don't have any experience with C++ or Windows development, so this project is probably not the best example of how to do things and is not very well optimized. If you have any suggestions, feel free to open an issue or a pull request.

The C++ code responsible for handling the Copy-on-write operations is borrowed from 0xbadfca11/reflink.

• Windows 11 and a Dev drive
• Node.js and npm (pnpm too, but it's optional)
• A C++ compiler compatible with your Node.js version (for building the native addon)

1. Clone this repository.

   gh repo clone nachoaldamav/refs-clone

2. Navigate into the project directory and install dependencies.

   cd refs-clone
   pnpm install

3. Build the native addon.

   pnpm build && pnpm compile

4. Run tests.

   pnpm test

import { cloneSync } from 'refs2-clone';
import path from 'path';

cloneSync('test.txt', 'test2.txt');

import { clone } from 'refs2-clone';
import path from 'path';

async function main() {
  await clone('test.txt', 'test2.txt');
}

Here are some benchmarks comparing the performance of the native addon with the functions fs.linkSync and fs.promises.link from the Node.js standard library.

Benchmark 1: node ./benchmarks/clone.js
  Time (mean ± σ):      34.3 ms ±   1.1 ms    [User: 1.9 ms, System: 1.5 ms]
  Range (min … max):    29.4 ms …  36.3 ms    40 runs

Benchmark 2: node ./benchmarks/cloneSync.js
  Time (mean ± σ):      33.2 ms ±   1.5 ms    [User: 2.1 ms, System: 1.4 ms]
  Range (min … max):    28.9 ms …  38.1 ms    43 runs

Benchmark 3: node ./benchmarks/link.js
  Time (mean ± σ):      28.2 ms ±   0.5 ms    [User: 3.2 ms, System: 3.2 ms]
  Range (min … max):    27.3 ms …  29.4 ms    47 runs

Benchmark 4: node ./benchmarks/linkSync.js
  Time (mean ± σ):      27.9 ms ±   0.7 ms    [User: 4.2 ms, System: 4.5 ms]
  Range (min … max):    26.9 ms …  29.5 ms    47 runs

Summary
  'node ./benchmarks/linkSync.js' ran
    1.01 ± 0.03 times faster than 'node ./benchmarks/link.js'
    1.19 ± 0.06 times faster than 'node ./benchmarks/cloneSync.js'
    1.23 ± 0.05 times faster than 'node ./benchmarks/clone.js'