PHP Cache like Rails.cache.fetch

cache.php

<?php
/**
 * PHP Cache class inspired by Rails.cache.fetch
 *
 * @author     Nicholas Valbusa - @squallstar
 * @copyright  Copyright (c) 2014, Nicholas Valbusa
 * @license    GNU/GPL (General Public License)
 * @link       https://gist.github.com/squallstar/9093354
 *
 */
 
class Cache
{
  // Make sure this directory exists
  const CACHE_PATH = 'tmp/';
  
  // Invalidate the cache by changing the version
  const CACHE_VERSION = '1';

  public static function fetch ($key = '', $callback)
  {
    $path = self::CACHE_PATH . self::CACHE_VERSION . $key . '.tmp';
    if (file_exists($path)) return unserialize(file_get_contents($path));

    try
    {
      $result = $callback(true);
    }
    catch (Exception $e)
    {
      var_dump($e);
      die;
    }

    if ($result === null) return $result;

    file_put_contents($path, serialize($result));
    return $result;
  }
}

usage.md

PHP Cache inspired by Rails cache

In Rails, you can do:

articles = Rails.cache.fetch "blog-articles" do
  BlogArticles.all
end

Therefore I created a simple class for my tiny PHP projects that will basically do the same. First of all, require the class:

<?php require_once 'cache.php';

And create a folder named tmp. Note that you can change it by updating the CACHE_PATH constant on the cache class.

Then, in a similar way you can do:

$articles = Cache::fetch("blog-articles", function() {
  return mysql_query("select * from blog_articles;");
});

The return can be any kind of object, since it will be serialized using PHP's built-in functions.

---

A nice way to use it in a real app is the following:

$user_projects = Cache::fetch("user-projects-" . $user->updated_at, function() {
  return mysql_query("select * from projects where user_id = $user->id;");
});

In the example above, anytime you will update the $user.updated_at timestamp, the cache will be invalidated.