Rate Limiting

The library integrates with Symfony Rate Limiter to manage how often the data source is contacted when cache entries expire.

Integration

Instead of implementing a custom interface, you can use any implementation of Symfony\Component\RateLimiter\LimiterInterface.

Example with Symfony Rate Limiter

use Symfony\Component\RateLimiter\RateLimiterFactory;
use Symfony\Component\RateLimiter\Storage\InMemoryStorage;

$factory = new RateLimiterFactory([
    'id' => 'my_api',
    'policy' => 'token_bucket',
    'limit' => 5,
    'rate' => ['interval' => '10 seconds'],
], new InMemoryStorage());

$limiter = $factory->create();

$manager = AsyncCacheBuilder::create($cache)
    ->withRateLimiter($limiter)
    ->build();

How It Interacts with Cache

When a cache item is stale and a refresh is needed: 1. The manager checks if a rate_limit_key is provided in CacheOptions. 2. It calls $limiter->consume(1). 3. If Accepted: The factory function is called to fetch fresh data. 4. If Rejected: - If serve_stale_if_limited is true and stale data exists, the stale data is returned. - Otherwise, a RateLimitException is thrown.

Benefit of Symfony Integration

By using Symfony Rate Limiter, you gain access to various storage backends (Redis, Database, PHP-APC) and sophisticated policies (Token Bucket, Fixed Window, Sliding Window) without additional configuration in this library.