Redis 是一种高级的键值存储系统，类似于 memcached，它将所有数据存储在内存中，因此每秒可以执行超过 10 万次的 GET 操作。
下面是我提出的解决方案：在 Redis 中缓存所有输出的 HTML 内容，而无需让 WordPress 重复执行页面脚本。使用 Redis 代替 Varnish 设置简单，而且可能更快。
安装 Redis
如果你使用的是 Debian 或其衍生操作系统，可以使用以下命令安装 Redis：
apt-get install redis-server
或者参考安装指南进行安装。
使用 Predis 作为 Redis 的 PHP 客户端
你需要一个客户端开发包，以便 PHP 可以连接到 Redis 服务。
我们推荐使用 Predis。将 predis.php 上传到 WordPress 的根目录。
前端缓存的 PHP 脚本
步骤 1：在 WordPress 的根目录中创建一个新文件 index-with-redis.php，内容如下：
<?php
// Change these two variables:
$seconds_of_caching = 60*60*24*7; // 7 days.
$ip_of_this_website = ‘204.62.14.112’;
/*
– 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. –>”;
}
?> 或者直接下载 index-with-redis.php
注意：将上述代码中的 IP 地址替换成你网站的 IP 地址
ps:
在 .htaccess 中将所有出现 index.php 的地方改为 index-with-redis.php ，如果你使用的是 Nginx 则修改 nginx.conf 中的 index.php 为 index-with-redis.php（并重载 Nginx : killall -s HUP nginx）。
