Caching Data in Symfony2

It is not too easy to enhance the performance of your application. In Symfony2 you could get benefit from caching. The most effective way to improve performance of an application is to cache the full output of a page and then bypass the application entirely on each subsequent request. The cache is the “middle-man” of the request-response communication between the client and your application. Caching data in Symfony2 with doctrine cache bundle can be implemented as described below.

Installing this bundle can be done through these simple steps:

1. Add this bundle to your project as a composer dependency:


// composer.json
{
    // ...
    require: {
        // ...
        "doctrine/doctrine-cache-bundle": "~1.0"
    }
}

2. Add this bundle in your application kernel:


// application/ApplicationKernel.php
public function registerBundles()
{
    // ...
    $bundles[] = new \Doctrine\Bundle\DoctrineCacheBundle\DoctrineCacheBundle();

    return $bundles;
}

Usage:

Simply use doctrine_cache.providers.{provider_name} to inject it into the desired service.

Check the following sample:


$apcCache = $this->container->get('doctrine_cache.providers.my_apc_cache');
$arrayCache = $this->container->get('doctrine_cache.providers.my_array_cache');

Usage Example for MongoDb:

In Your Config File


// config.yml

doctrine_cache:
    aliases:
        cache_categories: classifiad_category_cache
    providers:
        classifiad_category_cache:
            mongodb:
                server: mongodb://%mongodb_host%:%mongodb_port%
                database_name: %mongodb_database%

In Your Controller


// Saving Cached Data
$CategoryCacheProvider = $this->container->get('doctrine_cache.providers.classifiad_category_cache');
$CategoryCacheProvider->save('cache_categories', $categories, 60 * 60);

// Fetching Cached Data
$CategoryCacheProvider = $this->container->get('doctrine_cache.providers.classifiad_category_cache');
if ($CategoryCacheProvider->fetch('cache_categories')) {
    $categories = $CategoryCacheProvider->fetch('cache_categories');
}

Singleton Design Pattern in PHP

In software engineering, the singleton pattern is a design pattern that restricts the instantiation of a class to one object. This is useful when exactly one object is needed to coordinate actions across the system.

The following code is a simple implementation:



class Database
{
    // A static property to hold the single instance of the class
    private static $instance;

    // The constructor is private so that outside code cannot instantiate
    private function __construct() { }

    // All code that needs to get and instance of the class should call
    // this function like so: $db = Database::getInstance();
    public function getInstance()
    {
        // If there is no instance, create one
        if (!isset(self::$instance)) {
            $c = __CLASS__;
            self::$instance = new $c;
        }
        return self::$instance;
    }

    // Block the clone method
    private function __clone() {}
}

// To use, call the static method to get the only instance
$db = Database::getInstance();


Pros and Cons of Singeleton Design Pattern :

pro : You know you have the same instance available at all times.
con : One and only one instance is all you get.
pro : Instantiate itself for you so all you need to do is get it.
con : Autoinstantiation diminishes flexibility of argument passing.
pro : Since it is singeleton it can replace global variable declaration.
con : Since it is singeleton it can replace global variable declaration.