Directus ClosureCache

Directus ClosureCache is a simple way to cache slow runtime operations without much additional code or code re-organization. It implements a Slim-style method of naming and defining cached operations, either on-the-fly or in advance, and a one-line interface for warming pre-defined operations.

ClosureCache is a thin wrapper for the Zend\Cache module, which interfaces with numerous cache engines. It was built as a component of Directus6.

Install

To install via Composer, add the following to your composer.json:

{
    "require": {
        "drcts/closure-cache": "0.1.*"
    }
}

Examples

Initialize

The constructor accepts the same argument accepted by Zend\Cache\StorageFactory::factory: an array of options which identify the cache engine.

Memcached configuration

use Directus\ClosureCache\Cache;

$Cache = new Cache(array(
    'adapter' => 'memcached',
    'options' => array(
        'servers' => array(
            array('127.0.0.1', 11211)
        )
    )
));

Filesystem configuration

use Directus\ClosureCache\Cache;

$Cache = new Cache(array(
    'adapter' => 'filesystem',
    'options' => array(
        'cache_dir' => $cacheDir,
        'dir_level' => 2
    )
));

Cache on-the-fly

Cache slow operations on-the-fly this way:

list($resultA, $resultB) = $Cache->cache('slowOperationsAandB', function() {
	// ... running complex DB queries
	// ... fetching from lazy API
	return array($resultA, $resultB);
});

The function will only execute if the cache entry named slowOperationsAandB is undefined within cache storage.

Pre-defined, cached operations

To implement cache-warming and arguments for your cached operations, arrange them in advance using "definitions":

Here is a snippet from a hypothetical cacheDefinitions.php:

$Cache->define('siteMetadata', function() {
	// ... run a million database queries
	return $dataSet;
});

$Cache->define('userMetadata', function($userId) {
	// ... run a few database queries which take a $userId parameter
	return $userSpecificDataSet;
});

Now you can retrieve/warm these definitions from the rest of your application:

$siteMetadata = $Cache->warm('siteMetadata');

$user1 = $Cache->warm('userMetadata', array(1));
$user2 = $Cache->warm('userMetadata', array(2));

As before, the logic contained by the cache definitions will execute only if the corresponding entry (with or without argument modifiers) is undefined within the cache engine.

Cache expiration

Expire cache entries (defined above) at any time this way:

// Defined on the fly
$Cache->expire('slowOperationsAandB');

// Pre-defined
$Cache->expire('siteMetadata');

// Pre-defined w/ arguments
$Cache->expire('userMetadata', array(1));
$Cache->expire('userMetadata', array(2));

A note on serialization

All arguments and closure return values must be serializable via PHP's serialize function. Be sure to convert unserializable data to native/serializable PHP data types before passing them to a ClosureCache definition, or returning them from a callable passed to ClosureCache.