gistfile1.php

<?php

/**
 * Provides simple file-based caching for strings and arrays: 
 *
 *     // Set the "foo" cache
 *     Kohana::cache('foo', 'hello, world');
 *
 *     // Get the "foo" cache
 *     $foo = Kohana::cache('foo');
 *
 * All caches are stored as PHP code, generated with [var_export][ref-var].
 * Caching objects may not work as expected. Storing references or an
 * object or array that has recursion will cause an E_FATAL.
 * 
 * [ref-var]: http://php.net/var_export
 * 
 * @param   string   name of the cache
 * @param   mixed    data to cache
 * @param   integer  number of seconds the cache is valid for
 * @return  mixed    for getting
 * @return  boolean  for setting
 */
public function cache($name, $data = NULL, $lifetime = 60)
{
	// Cache file is a hash of the name
	$file = sha1($name).EXT;

	// Cache directories are split by keys
	$dir = APPPATH.'cache/'.$file[0].'/';

	if ($data === NULL)
	{
		if (is_file($dir.$file))
		{
			if ((time() - filemtime($dir.$file)) < $lifetime)
			{
				// Return the cache
				return include $dir.$file;
			}
			else
			{
				// Cache has expired
				unlink($dir.$file);
			}
		}

		// Cache not found
		return NULL;
	}

	if ( ! is_dir($dir))
	{
		// Create the cache directory
		mkdir($dir, 0777);
	}

	// Serialize the data and create the cache
	return (bool) file_put_contents($dir.$file, '<?php return '.var_export($data, TRUE).';');
}