🇬🇧󠁧󠁢󠁥󠁮󠁧󠁿 Symfony2 cache warmer

For this first post since 6 months, let me introduce to you the CacheWarmer class.

Cache warmer? What is this?

A cache warmer is just a class that writes in a file to store data. Really simple.

Look into you're app/cache directory. Here is an example of what you can find:

• Global configuration
• Translations
• Assetic configuration
• Doctrine proxies classes
• Twig compiled templates
• ...

Lot of things, created by cache warmers.

How to use cache warmer?

Juste create a file that extend the CacheWarmerInterface provided by the HttpKernel Component.

<?php

use Symfony\Component\HttpKernel\CacheWarmer\CacheWarmerInterface;

class MyCustomeCacheWarmer implements CacheWarmerInterface
{
    public function warmUp($cacheDir)
    {
        // Create a file here
        // Write in it
    }

    public function isOptional()
    {
        // By default, all CacheWarmer are called by the `app/console cache:warmup` command.
        // But you can specify the `--no-optional-warmers` to skip non optional ones.
        return false;
    }
}

For the implementation, you can take a look at the TemplatePathsCacheWarmer for example.

Of course, you have to declare your CacheWarmer as a service. Do not forget to tag it with kernel.cache_warmer:

<service id="my_custom.cache_warmer" class="path/to/MyCustomCacheWarmer">
    <tag name="kernel.cache_warmer" />
</service>

Now, if you run the command app/console cache:warmup (or app/console cache:clear without the --no-warmup option) your cache file should be created. (Search it in the app/cache/ folder).

To use your cached data, it's very simple. Look at TemplateLocator.

The TemplateLocator simply require the cached file and store the result into a var. To do the same thing, simply store a return statement in your file. For example, the app/cache/dev/templates.php file looks like this:

<?php return array (
    'template_name' => 'path/to/template',
    // ...
),

You're done. You can now use your custom CacheWarmer in your application. :)