Simple Cache Laravel Package

Getting Started

Start by requiring the interface package: composer require psr/simple-cache. This installs only the PSR-16 interface definitions—no caching backend. To get working caching, install a concrete implementation (e.g., symfony/cache with CacheItemPoolAdapter, league/cache, or use Laravel’s built-in adapter: cache()->driver() is PSR-16 compatible from Laravel 8.40+). Your first real use case will be injecting Psr\SimpleCache\CacheInterface into a service to cache lightweight results (e.g., a slow DB count or third-party API response) using get()/set().

Implementation Patterns

• Laravel services: Resolve CacheInterface via DI—e.g., public function __construct(CacheInterface $cache)—and use it directly in domain services, avoiding framework-specific Cache::remember() calls for portable code.
• Memoization helper: Wrap recurring logic like:

  $result = $cache->get("user_{$id}_stats", fn() => $this->expensiveStats($id), 300);
  

  (Note: TTL support depends on the underlying implementation; some accept int $ttl as third arg even if not in PSR-16 spec)
• Middleware caching: In HTTP middleware, cache short-lived response fragments (e.g., navigation counts, dashboard stats):

  $key = 'dashboard_' . md5($request->user()->id);
  if ($cache->has($key)) {
      return response()->setContent($cache->get($key));
  }
  // ... render, store, return
  

• Testing: Bind ArrayCache (from _aryie/array-cache) in phpunit.xml or test containers to avoid filesystem/network side effects.
• Interoperable libraries: Use when building packages that consume caching—e.g., an analytics bundle expecting CacheInterface—to maximize adoption.

Gotchas and Tips

• TTL ambiguity: PSR-16 v3.0 does not guarantee $ttl in set(). While many implementations (like Symfony’s adapter) accept set($key, $value, $ttl), it’s non-portable. For strict portability, use implementation-specific extensions or pass TTL via context (e.g., get($key, null, ['ttl' => 300]))—but this is not standardized.
• Null-safety: If null is a valid cached value, get($key)’s default behavior returns null on miss—leading to false positives. Always use has($key) first or specify a unique sentinel as $default (e.g., get($key, self::CACHE_MISS_SENTINEL)).
• PHP version trap: PSR-16 v3 requires PHP 8+. If your project targets PHP 7.4, you must use ^2.0 (composer require psr/simple-cache:^2.0). Conflicts with newer implementations often break silently.
• Bulk operations: Prefer getMultiple() over looping get()—e.g., getMultiple(['config_a', 'config_b'])—to avoid cache round-trips.
• Key validation: Implementations like symfony/cache may throw InvalidArgumentException for non-string keys or serialize()-unsafe values. Always ensure keys are strings/scalars and values are serializable.
• No eviction policy: PSR-16 doesn’t define LRU/LFU—rely on your underlying store (Redis, APCu, file) for memory management. Don’t assume items expire unless TTL is explicitly supported and enforced by the driver.