WordPress plugin for embedding gists

gist-embed.php

<?php
/*
Plugin Name: Gist Embed
Description: Embed Gists from Github with robust caching
Author: David Evans
Version: 0.1
*/


function robust_cache($callback, $args, $key, $success_retry, $failure_retry, $expire)
{
	$data = get_transient($key);
	
	if ($data)
	{
		// If the last result is still valid just return it
		if (isset($data['next_attempt']) AND $data['next_attempt'] > time())
		{
			return $data['result'];
		}
	}
	// If there's no cached result, initialize
	else
	{
		$data = array('result' => FALSE);
	}
	
	$result = call_user_func_array($callback, (array) $args);
	
	if ($result !== FALSE)
	{
		$data['next_attempt'] = time() + $success_retry;
		$data['result'] = $result;
	}
	else
	{
		$data['next_attempt'] = time() + $failure_retry;
	}
	
	set_transient($key, $data, $expires);
	
	return $data['result'];
}

function gist_embed_fetch_html($id)
{
	$context = stream_context_create(array('http' => array
	(
		'timeout' => 2
	)));
	
	$response = @file_get_contents("http://gist.github.com/$id.json", 0, $context);

	if ($response)
	{
		$response = @json_decode($response);
		return empty($response->div) ? FALSE : $response->div;
	}
	
	return FALSE;
}

function gist_embed_shortcode($atts)
{
	if (empty($atts['id'])) return NULL;
	
	return robust_cache
	(
		'gist_embed_fetch_html',
		$atts['id'],
		'gist_embed_'.$atts['id'],
		// Retry 24 hours after success
		24 * 60 * 60,
		// Retry 1 hour after failure
		60 * 60,
		// Expire cache if it's not touched for 120 days
		120 * 24 * 60 * 60
	);
}

add_shortcode('gist', 'gist_embed_shortcode');