memoization.md

Memoization

Memoization is an optimization technique that caches the result of expensive processes for the duration of the request. This type of caching is handled by the Titon\Common\Cacheable and Titon\Common\StaticCacheable traits.

class Foo {
    use Titon\Common\Cacheable;
}

// Static class
class Bar {
    use Titon\Common\StaticCacheable;
}

The API for StaticCacheable is the same as Cacheable, excluding toggle support.

Caching Data

There are 2 ways to cache data in the class -- the first being the preferred way, using cache(). The cache() method handles the automatic checking, fetching, and caching of data through a callback.

public function doExpensiveProcess(): mixed {
    return $this->cache(__METHOD__, ($self) ==> {
        // Expensive calculation
    });
}

In the example above, if the key defined by __METHOD__ exists, then the cached result is returned, else it is set using the value from the defined callback.

The class instance is passed as the 1st argument to the callback. This does not apply when using StaticCacheable.

The other way to cache data, is with the setCache() method. This method is useful when you want to manually handle the entire checking and fetching process using different steps. The following example is functionality equivalent to cache().

public function doExpensiveProcess(): mixed {
    $key = $this->createCacheKey(__METHOD__);

    if ($this->hasCache($key)) {
        return $this->getCache($key);
    }

    // Expensive calculation

    return $this->setCache($key, $value);
}

Retrieving Data

Besides the cache() method mentioned previously, the getCache() method is used for retrieving an item by a unique key. If the key does not exist, then null is returned.

$this->getCache('foo'); // Cached value or null

Removing Cached Items

To remove a cached item, use the removeCache() method.

$this->removeCache('foo');

Or to remove all cached items, use flushCache().

$this->flushCache();

Toggling Caching

There may be times where caching needs to be disabled for a short duration. This can be achieved with the toggleCache() method. The method accepts a boolean, which either enables or disables caching.

$this->toggleCache(false); // Disable

// Do something that shouldn't be cached

$this->toggleCache(true); // Enable

To check the state of caching, use the isCacheEnabled() method.

Creating Unique Keys

To create a unique cache key, one can use the createCacheKey() method. This method accepts scalar and traversable values. When a traversable is used, each item is separated with a - and optionally hashed.

$this->createCacheKey('foo'); // foo
$this->createCacheKey(['foo', 'bar']); // foo-bar
$this->createCacheKey(['foo', 'bar', ['nested', 'array']]); // foo-bar-d3e545e5b6dd7d1c9c7be76d5bb18241

This method is automatically called within all the other methods.