Reactive and Asynchronous Rate Limiter in PHP

A reactive and asynchronous rate limiter in PHP, designed to handle high-frequency requests efficiently, this implementation leverages pcntl signals to provide non-blocking and lock-free request handling. It is a lightweight solution ideal for applications requiring precise and dynamic control over incoming request rates.

Features

• Reactive and Asynchronous: - Utilizes PHP's `pcntl` library to process incoming requests reactively. - Ensures non-blocking behavior, making it suitable for high-concurrency environments.
• No Locking Required: - Eliminates the need for semaphores, file locks, or databases. - Tracks requests entirely in memory for lightweight operation.
• Dynamic Rate Management: - Configurable maximum requests per time window. - Handles blocked requests reactively with customizable timeout durations.

Code Overview

Core Class

The implementation includes the ReactiveRateLimiter class, which: 1. Dynamically tracks requests in memory. 2. Reacts to incoming signals using pcntl_signal for efficient concurrency. 3. Implements rate-limiting logic to allow or block requests based on defined thresholds.

Example Usage

<?php
include 'ReactiveRateLimiter.php';

// Allow 5 requests every 5 seconds
$rateLimiter = new ReactiveRateLimiter(5, 5.0); 	

// Simulate periodic requests
while (true) {
    $rateLimiter->sendRequest();
    usleep(200000); // 0.2 seconds between requests
}
?>