Redis是一个高级的key-value存储系统,类似memcached,所有内容都存在内存中,因此每秒钟可以超过10万次GET操作。

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。

安装 Redis

如果你使用的是 Debian 或者衍生的操作系统可使用如下命令安装 Redis:

apt-get install redis-server

或者阅读 安装指南

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 服务上。

这里我们推荐 Predis. 上传 predis.php 到 WordPress 的根目录。

前端缓存的PHP脚本

步骤1:在WordPress 的根目录创建新文件 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 Predis\Client('');

// 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

步骤2:将上述代码中的 IP 地址替换成你网站的 IP 地址

步骤3: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)。

性能测试

1.没有Redis 的情况下,平均首页执行1.614 秒,文章页0.174 秒(无任何缓存插件)

2.使用Redis 的情况下,平均页面执行时间0.00256秒

我已经在我的博客中使用了如上的方法进行加速很长时间了,一切运行良好。

其他建议

我的环境是Nginx + PHP-FPM + APC + Cloudflare + Redis. 安装在一个 nano VPS 中,无缓存插件。

请确认使用了gzip压缩,可加快访问速度。

访问 wp-admin

要访问 wp-admin 必须使用 /wp-admin/index.php 代替原来的 /wp-admin/.

原文:jimwestergren 编译:oschina