PHP File-System Cache

I’m just sharing a couple of functions I created a while back to cache some resource-intensive processed dada for quick and easy access. This is pretty ideal for large amounts of data and it’s very simple to set up. The beauty of this is that you can store just about any data type – it doesn’t have to be a string.

Just setup the cache directory to have proper read/write permissions (preferably in a non-accessible from web directory). Then use the two functions.

Example usage:

// The 2nd argument, $hours is how long to retain data before getting new
$contents = get_cache('TEST_KEY', 24);
if ($contents === false) {
	// This is where you'd get data from an API, DB or whatever
	$contents = 'Just some example contents';
	set_cache('TEST_KEY', $contents);
echo $contents;


define('CACHE_DIR', 'cache/'); // Include trailing slash

function get_cache($key, $hours) {
	$file = CACHE_DIR . md5($key) . '.cache';
	if (!file_exists($file) || filemtime($file) < time() - $hours * 3600)
		return false;
	return unserialize(file_get_contents($file));

function set_cache($key, $value) {
	$file = CACHE_DIR . md5($key) . '.cache';
	file_put_contents($file, serialize($value));

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