Simple PDO to File Cache for PHP

gistfile1.php

<?php
// This is a simple way to cache queries to your local filesystem while maintaining control over their freshness.
// Great for those nasty archival queries that data changes don't happen to.
// Free to all, forever - John Vilsack 2014


$file = './cache/**FILENAME**.cache'; // Path and name of .cache file
$expire = 900; // # of seconds before cache is stale

// Function to create the cached file.
function makeCache($file) {

	// Create PDO connection
	$pdo = new PDO('mysql:host=**HOST**;port=**PORT**;dbname=**DATABASE**', '**DBUSER**', '**DBPASSWORD**');

	// Do your thing
	$query = $pdo->prepare('**SQLSTATEMENT**');
	$query->execute();
	$result = $query->fetchAll();
	unset($query);

	// OPTIONAL: Encode array in JSON
	$result = json_encode($result);

	// Put data in file.
	$fp = fopen($file,"w");
	fputs($fp,$result);
	fclose($fp);

	// You need whatever you just cached, so return it.
	return $result;

}

// Function to check cache and retrieve its bits.
function checkCache($file) {

	// Check file create time vs. your expire.
	if (filemtime($file) < (time() - $expire)) {
		$result = makeCache($file);
	} else {
		// It's cached and it's current, so retrieve it.
		$result = file_get_contents($file);
	}

	return $result;
}

// Your new, tidy way of retrieving data while setting a cache.
$data = file_exists($file) ? checkCache($file) : makeCache($file);