Cache Laravel Package

Getting Started

Minimal Setup

1. Installation:

   composer require guzzle/cache
   

   Ensure compatibility with Guzzle 3.x (this package is a read-only subtree split).

2. Basic Usage:

   use Guzzle\Cache\Cache;
   use Guzzle\Cache\Storage\FileCacheStorage;
   
   // Initialize cache storage (e.g., file-based)
   $storage = new FileCacheStorage('/path/to/cache/dir');
   $cache = new Cache($storage);
   
   // Store a value
   $cache->save('key', 'value', 3600); // Expires in 1 hour
   
   // Retrieve a value
   $value = $cache->fetch('key');
   

3. First Use Case: Cache HTTP responses to avoid redundant API calls:

   use Guzzle\Http\Client;
   use Guzzle\Cache\CacheMiddleware;
   
   $client = new Client();
   $client->getEmitter()->attach(new CacheMiddleware($cache));
   $response = $client->get('https://api.example.com/data');
   

Implementation Patterns

Common Workflows

1. Middleware Integration: Use CacheMiddleware to cache HTTP responses globally:

   $client = new Client();
   $client->getEmitter()->attach(new CacheMiddleware($cache, [
       'default_ttl' => 3600,
       'private_ttl' => 86400,
   ]));
   

2. Conditional Caching: Cache only successful responses (e.g., 2xx status codes):

   $client->getEmitter()->attach(function ($request, $event) use ($cache) {
       if ($event->getResponse()->isSuccess()) {
           $cache->save($request->getUrl(), $event->getResponse(), 3600);
       }
   });
   

3. Custom Storage: Extend CacheStorageInterface for database or Redis backends:

   class RedisCacheStorage implements CacheStorageInterface {
       // Implement save(), fetch(), delete(), etc.
   }
   

Integration Tips

• Laravel Integration: Use guzzle/cache with Laravel's HTTP client (if compatible) or wrap it in a service:

  $this->app->singleton('cache', function ($app) {
      $storage = new FileCacheStorage(storage_path('cache/guzzle'));
      return new Cache($storage);
  });
  

• Cache Invalidation: Manually clear stale data:

  $cache->delete('key'); // Delete specific key
  $cache->clear();       // Clear all cached data
  

Gotchas and Tips

Pitfalls

1. Guzzle 3 Compatibility:

   • This package is Guzzle 3.x only. Avoid mixing with Guzzle 6/7.
   • Use guzzlehttp/guzzle (v6+) for newer projects; this package is legacy.

2. Thread Safety:

   • File-based storage (FileCacheStorage) is not thread-safe. Use locks or switch to Redis/Memcached for concurrent apps.

3. Serialization:

   • Only serializable data can be cached. Avoid objects without __serialize()/__unserialize().

Debugging

• Cache Misses: Check if keys are being generated correctly (e.g., URL hashing in CacheMiddleware).

  $cache->has('key'); // Verify key existence
  

• Storage Issues: Ensure the cache directory is writable:

  chmod -R 775 /path/to/cache/dir
  

Extension Points

1. Custom Cache Keys: Override CacheMiddleware::getCacheKey() to customize key generation:

   $middleware = new CacheMiddleware($cache, [
       'cache_key' => function ($request) {
           return md5($request->getUrl() . $request->getMethod());
       }
   ]);
   

2. Event Hooks: Extend CacheMiddleware to log cache hits/misses:

   $client->getEmitter()->attach(function ($request, $event) use ($cache) {
       if ($cache->has($request->getUrl())) {
           Log::debug('Cache hit for', ['url' => $request->getUrl()]);
       }
   });
   

3. Fallback Logic: Combine with Guzzle\Plugin\Retry to retry failed requests after cache misses:

   $client->getEmitter()->attach(new RetryPlugin());
   $client->getEmitter()->attach(new CacheMiddleware($cache));