dtl-js/src/js/utils/benchmark_getRandomValues.js

Data Transformation Language - JSON templates and data transformation

const { performance } = require('perf_hooks');
const crypto = require('crypto');

let getRandomValues = crypto.webcrypto.getRandomValues.bind(crypto.webcrypto);

function random_number_up_to_rejection(max) {
    if (max <= 0 || max > 0xFFFFFFFF) {
        throw new RangeError('max must be between 1 and 2^32-1');
    }
    
    const value_array = new Uint32Array(1);
    const max_acceptable_value = Math.floor((0xFFFFFFFF + 1) / max) * max - 1;

    let result;
    do {
        getRandomValues(value_array);
        result = value_array[0];
    } while (result > max_acceptable_value);

    return result % max;
}

function random_number_up_to_batch(max) {
    if (max <= 0 || max > 0xFFFFFFFF) {
        throw new RangeError('max must be between 1 and 2^32-1');
    }
    
    const value_array_size = 128; // Size of the array to generate random values
    const value_array = new Uint32Array(value_array_size);
    const max_acceptable_value = Math.floor((0xFFFFFFFF + 1) / max) * max - 1;

    while (true) {
        getRandomValues(value_array);
        for (let i = 0; i < value_array.length; i++) {
            if (value_array[i] <= max_acceptable_value) {
                return value_array[i] % max;
            }
        }
    }
}

function benchmark(func, max, iterations) {
    const start = performance.now();
    for (let i = 0; i < iterations; i++) {
        func(max);
    }
    const end = performance.now();
    return end - start;
}

const max = 250000;
const iterations = 500000;

const timeRejection = benchmark(random_number_up_to_rejection, max, iterations);
console.log(`Rejection Sampling: ${timeRejection} ms`);

const timeBatch = benchmark(random_number_up_to_batch, max, iterations);
console.log(`Batch Generation: ${timeBatch} ms`);