让 WordPress 使用 Redis 缓存来进行加速

我下面提出的解决方案是在 Redis 中缓存所有输出的 HTML 内容而无需再让 WordPress 重复执行页面脚本。这里使用 Redis 代替 Varnish 设置简单，而且可能更快。

/*

– This file is written by Jim Westergren, copyright all rights reserved.
– See more here: www.jimwestergren.com/WordPress-with-redis-as-a-frontend-cache/
– The code is free for everyone to use how they want but please mention my name and link to my article when writing about this.
– Change $ip_of_this_website to the IP of your website above.
– Add ?refresh=yes to the end of a URL to refresh it’s cache
– You can also enter the redis client via the command prompt with the command “redis-cli” and then remove all cache with the command “flushdb”.

*/

// Very necessary if you use Cloudfare:

if (isset($_SERVER[‘HTTP_CF_CONNECTING_IP’])) {
$_SERVER[‘REMOTE_ADDR’] = $_SERVER[‘HTTP_CF_CONNECTING_IP’];
}

// This is from WordPress:

define(‘WP_USE_THEMES’, true);

// Start the timer:

function getmicrotime($t) {
list($usec, $sec) = explode(” “,$t);
return ((float)$usec + (float)$sec);
}

$start = microtime();

// Initiate redis and the PHP client for redis:

include(“predis.php”);
$redis = new PredisClient(”);

// few variables:

$current_page_url = “http://”.$_SERVER[‘HTTP_HOST’].$_SERVER[‘REQUEST_URI’];

$current_page_url = str_replace(‘?refresh=yes’, ”, $current_page_url);

$redis_key = md5($current_page_url);

// This first case is either manual refresh cache by adding ?refresh=yes after the URL or somebody posting a comment

if (isset($_GET[‘refresh’]) || substr($_SERVER[‘REQUEST_URI’], -12) == ‘?refresh=yes’ || ($_SERVER[‘HTTP_REFERER’] == $current_page_url && $_SERVER[‘REQUEST_URI’] != ‘/’ && $_SERVER[‘REMOTE_ADDR’] != $ip_of_this_website)) {
require(‘./wp-blog-header.php’);
$redis->del($redis_key);

// Second case: cache exist in redis, let’s display it

} else if ($redis->exists($redis_key)) {

$html_of_current_page = $redis->get($redis_key);

echo $html_of_current_page;

echo “<!– This is cache –>”;

// third: a normal visitor without cache. And do not cache a preview page from the wp-admin:

} else if ($_SERVER[‘REMOTE_ADDR’] != $ip_of_this_website && strstr($current_page_url, ‘preview=true’) == false) {
require(‘./wp-blog-header.php’);
$html_of_current_page = file_get_contents($current_page_url);
$redis->setex($redis_key, $seconds_of_caching, $html_of_current_page);
echo “<!– Cache has been set –>”;

// last case: the normal WordPress. Should only be called with file_get_contents:

} else {
require(‘./wp-blog-header.php’);
}

// Let’s display some page generation time (note: CloudFlare may strip out comments):

$end = microtime();
$t2 = (getmicrotime($end) – getmicrotime($start));
if ($_SERVER[‘REMOTE_ADDR’] != $ip_of_this_website) {
echo “<!– Cache system by Jim Westergren. Page generated in “.round($t2,5).” seconds. –>”;
}
?>