Basic PHP Redis page cache

redis-cache.php

<?php
// change vars here
$cf = 1;            // set to 1 if you are using cloudflare
$debug = 0;         // set to 1 if you wish to see execution time and cache actions
$display_powered_by_redis = 0;  // set to 1 if you want to display a powered by redis message with execution time, see below

$start = microtime();   // start timing page exec

// if cloudflare is enabled
if ($cf) {
    if (isset($_SERVER['HTTP_CF_CONNECTING_IP'])) {
        $_SERVER['REMOTE_ADDR'] = $_SERVER['HTTP_CF_CONNECTING_IP'];
    }
}

// from wp
define('WP_USE_THEMES', true);

// init predis
$redis = new Redis();
$redis->connect(parse_url($_ENV['REDISTOGO_URL'], PHP_URL_HOST), parse_url($_ENV['REDISTOGO_URL'], PHP_URL_PORT));
if (!is_array(parse_url($_ENV['REDISTOGO_URL'], PHP_URL_PASS))) {
	$redis->auth(parse_url($_ENV['REDISTOGO_URL'], PHP_URL_PASS));
}

// init vars
$domain = $_SERVER['HTTP_HOST'];
$url = "http://".$_SERVER['HTTP_HOST'].$_SERVER['REQUEST_URI'];
$url = str_replace('?r=y', '', $url);
$url = str_replace('?c=y', '', $url);
$dkey = md5($domain);
$ukey = md5($url);

// check if page isn't a comment submission
(isset($_SERVER['HTTP_CACHE_CONTROL']) && $_SERVER['HTTP_CACHE_CONTROL'] == 'max-age=0') ? $submit = 1 : $submit = 0;

// check if a cache of the page exists
if ( $redis->hexists($dkey, $ukey) ) {
    echo $redis->hget($dkey, $ukey);
    $cached = 1;
    $msg = 'this is a cache';
// if a comment was submitted or clear page cache request was made delete cache of page
} else if (substr($_SERVER['REQUEST_URI'], -4) == '?r=y') {
    $redis->hdel($dkey, $ukey);
    $msg = 'cache of page deleted';
// delete entire cache, works only if logged in
} else if (substr($_SERVER['REQUEST_URI'], -4) == '?c=y') {
    if ($redis->exists($dkey)) {
        $redis->del($dkey);
        $msg = 'domain cache flushed';
    } else {
        $msg = 'no cache to flush';
    }
// cache the page
} else {
	// turn on output buffering
	ob_start();

	// get contents of output buffer
	$html = ob_get_contents();

	// clean output buffer
	ob_end_clean();
	echo $html;

	// store html contents to redis cache
	$redis->hset($dkey, $ukey, $html);
	$msg = 'cache is set';
}

$end = microtime(); // get end execution time

// show messages if debug is enabled
if ($debug) {
    echo $msg.': ';
    echo t_exec($start, $end);
}

if ($cached && $display_powered_by_redis) {
    // You should move this CSS to your CSS file and change the: float:right;margin:20px 0;
    echo "<style>#redis_powered{float:right;margin:20px 0;background:url(http://images.staticjw.com/jim/3959/redis.png) 10px no-repeat #fff;border:1px solid #D7D8DF;padding:10px;width:190px;}
    #redis_powered div{width:190px;text-align:right;font:10px/11px arial,sans-serif;color:#000;}</style>";
    echo "<a href=\"http://www.jimwestergren.com/wordpress-with-redis-as-a-frontend-cache/\" style=\"text-decoration:none;\"><div id=\"redis_powered\"><div>Page generated in<br/> ".t_exec($start, $end)." sec</div></div></a>";
}

// time diff
function t_exec($start, $end) {
    $t = (getmicrotime($end) - getmicrotime($start));
    return round($t,5);
}

// get time
function getmicrotime($t) {
    list($usec, $sec) = explode(" ",$t);
    return ((float)$usec + (float)$sec);
}

?>