object-cache.php

<?php
/*
 * Plugin Name:  KDK Memcached Object Cache (by Kodeka)
 * Plugin URI:   https://github.com/kodeka/kdk_memcached_object_cache
 * Description:  Object cache driver for Memcached in WordPress. Based on Memcached Redux. Upload this file to your WordPress site's /wp-content/ folder. Setup multiple Memcached backends by defining them in wp-config. Check the plugin repo on GitHub for further instructions.
 * Version:      1.1
 * Author:       Fotis Alexandrou (using code from Scott Taylor, Ryan Boren, Denis de Bernardy, Matt Martz, Mike Schroder, Mika Epstein)
 * Author URI:   https://kodeka.io
 * License:      GNU/GPL https://www.gnu.org/copyleft/gpl.html
 */

if (!defined('WP_CACHE_KEY_SALT')) {
    define('WP_CACHE_KEY_SALT', md5(dirname(__FILE__)));
}

if (class_exists('Memcached')) {
    function wp_cache_add($key, $data, $group = '', $expire = 0)
    {
        global $wp_object_cache;

        return $wp_object_cache->add($key, $data, $group, $expire);
    }

    function wp_cache_incr($key, $n = 1, $group = '')
    {
        global $wp_object_cache;

        return $wp_object_cache->incr($key, $n, $group);
    }

    function wp_cache_decr($key, $n = 1, $group = '')
    {
        global $wp_object_cache;

        return $wp_object_cache->decr($key, $n, $group);
    }

    function wp_cache_close()
    {
        global $wp_object_cache;

        return $wp_object_cache->close();
    }

    function wp_cache_delete($key, $group = '')
    {
        global $wp_object_cache;

        return $wp_object_cache->delete($key, $group);
    }

    function wp_cache_flush()
    {
        global $wp_object_cache;

        return $wp_object_cache->flush();
    }

    function wp_cache_get($key, $group = '', $force = false, &$found = null)
    {
        global $wp_object_cache;

        return $wp_object_cache->get($key, $group, $force, $found);
    }

    /**
     * $keys_and_groups = array(
     *      array( 'key', 'group' ),
     *      array( 'key', '' ),
     *      array( 'key', 'group' ),
     *      array( 'key' )
     * );
     *
     */
    function wp_cache_get_multi($key_and_groups, $bucket = 'default')
    {
        global $wp_object_cache;

        return $wp_object_cache->get_multi($key_and_groups, $bucket);
    }

    /**
     * $items = array(
     *      array( 'key', 'data', 'group' ),
     *      array( 'key', 'data' )
     * );
     *
     */
    function wp_cache_set_multi($items, $expire = 0, $group = 'default')
    {
        global $wp_object_cache;

        return $wp_object_cache->set_multi($items, $expire = 0, $group = 'default');
    }

    function wp_cache_init()
    {
        global $wp_object_cache;

        $wp_object_cache = new WP_Object_Cache();
    }

    function wp_cache_replace($key, $data, $group = '', $expire = 0)
    {
        global $wp_object_cache;

        return $wp_object_cache->replace($key, $data, $group, $expire);
    }

    function wp_cache_set($key, $data, $group = '', $expire = 0)
    {
        global $wp_object_cache;

        if (defined('WP_INSTALLING') == false) {
            return $wp_object_cache->set($key, $data, $group, $expire);
        } else {
            return $wp_object_cache->delete($key, $group);
        }
    }

    function wp_cache_add_global_groups($groups)
    {
        global $wp_object_cache;

        $wp_object_cache->add_global_groups($groups);
    }

    function wp_cache_add_non_persistent_groups($groups)
    {
        global $wp_object_cache;

        $wp_object_cache->add_non_persistent_groups($groups);
    }

    class WP_Object_Cache
    {
        public $global_groups = array();
        public $no_mc_groups = array();
        public $cache = array();
        public $mc = array();
        public $stats = array();
        public $group_ops = array();
        public $cache_enabled = true;
        public $default_expiration = 0;

        public function add($id, $data, $group = 'default', $expire = 0)
        {
            $key = $this->key($id, $group);

            if (is_object($data)) {
                $data = clone $data;
            }

            if (in_array($group, $this->no_mc_groups)) {
                $this->cache[$key] = $data;
                return true;
            } elseif (isset($this->cache[$key]) && $this->cache[$key] !== false) {
                return false;
            }

            $mc =& $this->get_mc($group);
            $expire = ($expire == 0) ? $this->default_expiration : $expire;
            $result = $mc->add($key, $data, $expire);

            if (false !== $result) {
                ++$this->stats['add'];
                $this->group_ops[$group][] = "add $id";
                $this->cache[$key] = $data;
            }

            return $result;
        }

        public function __destruct()
        {
            $this->close();
            foreach ($this->mc as $bucket => $mc) {
                $mc->resetServerList();
            }
        }

        public function add_global_groups($groups)
        {
            if (! is_array($groups)) {
                $groups = (array) $groups;
            }

            $this->global_groups = array_merge($this->global_groups, $groups);
            $this->global_groups = array_unique($this->global_groups);
        }

        public function add_non_persistent_groups($groups)
        {
            if (! is_array($groups)) {
                $groups = (array) $groups;
            }

            $this->no_mc_groups = array_merge($this->no_mc_groups, $groups);
            $this->no_mc_groups = array_unique($this->no_mc_groups);
        }

        public function incr($id, $n = 1, $group = 'default')
        {
            $key = $this->key($id, $group);
            $mc =& $this->get_mc($group);
            $this->cache[ $key ] = $mc->increment($key, $n);
            return $this->cache[ $key ];
        }

        public function decr($id, $n = 1, $group = 'default')
        {
            $key = $this->key($id, $group);
            $mc =& $this->get_mc($group);
            $this->cache[ $key ] = $mc->decrement($key, $n);
            return $this->cache[ $key ];
        }

        public function close()
        {
            foreach ($this->mc as $bucket => $mc) {
                $mc->quit();
            }

            return true;
        }

        public function delete($id, $group = 'default')
        {
            $key = $this->key($id, $group);

            if (in_array($group, $this->no_mc_groups)) {
                unset($this->cache[$key]);
                return true;
            }

            $mc =& $this->get_mc($group);

            $result = $mc->delete($key);

            if (false !== $result) {
                ++$this->stats['delete'];
                $this->group_ops[$group][] = "delete $id";
                unset($this->cache[$key]);
            }

            return $result;
        }

        public function flush()
        {
            // Don't flush if multi-blog.
            if (function_exists('is_site_admin') || defined('CUSTOM_USER_TABLE') && defined('CUSTOM_USER_META_TABLE')) {
                return true;
            }

            $ret = true;
            foreach (array_keys($this->mc) as $group) {
                $ret &= $this->mc[$group]->flush();
            }
            return $ret;
        }

        public function get($id, $group = 'default', $force = false, &$found = null)
        {
            $key = $this->key($id, $group);
            $mc =& $this->get_mc($group);
            $found = false;

            if (isset($this->cache[$key]) && (!$force || in_array($group, $this->no_mc_groups))) {
                $found = true;
                if (is_object($this->cache[$key])) {
                    $value = clone $this->cache[$key];
                } else {
                    $value = $this->cache[$key];
                }
            } elseif (in_array($group, $this->no_mc_groups)) {
                $this->cache[$key] = $value = false;
            } else {
                $value = $mc->get($key);
                if ($value === false || (is_integer($value) && -1 == $value)) {
                    // $value = false;
                    $found = $mc->getResultCode() !== Memcached::RES_NOTFOUND;
                } else {
                    $found = true;
                }
                $this->cache[$key] = $value;
            }

            if ($found) {
                ++$this->stats['get'];
                $this->group_ops[$group][] = "get $id";
            } else {
                ++$this->stats['miss'];
            }

            if ('checkthedatabaseplease' === $value) {
                unset($this->cache[$key]);
                $value = false;
            }

            return $value;
        }

        public function get_multi($keys, $group = 'default')
        {
            $return = array();
            $gets = array();
            foreach ($keys as $i => $values) {
                $mc =& $this->get_mc($group);
                $values = (array) $values;
                if (empty($values[1])) {
                    $values[1] = 'default';
                }

                list($id, $group) = (array) $values;
                $key = $this->key($id, $group);

                if (isset($this->cache[$key])) {
                    if (is_object($this->cache[$key])) {
                        $return[$key] = clone $this->cache[$key];
                    } else {
                        $return[$key] = $this->cache[$key];
                    }
                } elseif (in_array($group, $this->no_mc_groups)) {
                    $return[$key] = false;
                } else {
                    $gets[$key] = $key;
                }
            }

            if (!empty($gets)) {
                $results = $mc->getMulti($gets, $null, Memcached::GET_PRESERVE_ORDER);
                $joined = array_combine(array_keys($gets), array_values($results));
                $return = array_merge($return, $joined);
            }

            ++$this->stats['get_multi'];
            $this->group_ops[$group][] = "get_multi $id";
            $this->cache = array_merge($this->cache, $return);
            return array_values($return);
        }

        public function key($key, $group)
        {
            if (empty($group)) {
                $group = 'default';
            }

            if (false !== array_search($group, $this->global_groups)) {
                $prefix = $this->global_prefix;
            } else {
                $prefix = $this->blog_prefix;
            }

            return preg_replace('/\s+/', '', WP_CACHE_KEY_SALT . "$prefix$group:$key");
        }

        public function replace($id, $data, $group = 'default', $expire = 0)
        {
            $key = $this->key($id, $group);
            $expire = ($expire == 0) ? $this->default_expiration : $expire;
            $mc =& $this->get_mc($group);

            if (is_object($data)) {
                $data = clone $data;
            }

            $result = $mc->replace($key, $data, $expire);
            if (false !== $result) {
                $this->cache[$key] = $data;
            }
            return $result;
        }

        public function set($id, $data, $group = 'default', $expire = 0)
        {
            $key = $this->key($id, $group);
            if (isset($this->cache[$key]) && ('checkthedatabaseplease' === $this->cache[$key])) {
                return false;
            }

            if (is_object($data)) {
                $data = clone $data;
            }

            $this->cache[$key] = $data;

            if (in_array($group, $this->no_mc_groups)) {
                return true;
            }

            $expire = ($expire == 0) ? $this->default_expiration : $expire;
            $mc =& $this->get_mc($group);
            $result = $mc->set($key, $data, $expire);

            return $result;
        }

        public function set_multi($items, $expire = 0, $group = 'default')
        {
            $sets = array();
            $mc =& $this->get_mc($group);
            $expire = ($expire == 0) ? $this->default_expiration : $expire;

            foreach ($items as $i => $item) {
                if (empty($item[2])) {
                    $item[2] = 'default';
                }

                list($id, $data, $group) = $item;

                $key = $this->key($id, $group);
                if (isset($this->cache[$key]) && ('checkthedatabaseplease' === $this->cache[$key])) {
                    continue;
                }

                if (is_object($data)) {
                    $data = clone $data;
                }

                $this->cache[$key] = $data;

                if (in_array($group, $this->no_mc_groups)) {
                    continue;
                }

                $sets[$key] = $data;
            }

            if (!empty($sets)) {
                $mc->setMulti($sets, $expire);
            }
        }

        public function colorize_debug_line($line)
        {
            $colors = array(
            'get'   => 'green',
            'set'   => 'purple',
            'add'   => 'blue',
            'delete'=> 'red'
        );

            $cmd = substr($line, 0, strpos($line, ' '));

            $cmd2 = "<span style='color:{$colors[$cmd]}'>$cmd</span>";

            return $cmd2 . substr($line, strlen($cmd)) . "\n";
        }

        public function stats()
        {
            echo "<p>\n";
            foreach ($this->stats as $stat => $n) {
                echo "<strong>$stat</strong> $n";
                echo "<br/>\n";
            }
            echo "</p>\n";
            echo "<h3>Memcached:</h3>";
            foreach ($this->group_ops as $group => $ops) {
                if (!isset($_GET['debug_queries']) && 500 < count($ops)) {
                    $ops = array_slice($ops, 0, 500);
                    echo "<big>Too many to show! <a href='" . add_query_arg('debug_queries', 'true') . "'>Show them anyway</a>.</big>\n";
                }
                echo "<h4>$group commands</h4>";
                echo "<pre>\n";
                $lines = array();
                foreach ($ops as $op) {
                    $lines[] = $this->colorize_debug_line($op);
                }
                print_r($lines);
                echo "</pre>\n";
            }

            if (!empty($this->debug) && $this->debug) {
                var_dump($this->memcache_debug);
            }
        }

        public function &get_mc($group)
        {
            if (isset($this->mc[$group])) {
                return $this->mc[$group];
            }
            return $this->mc['default'];
        }

        public function __construct()
        {
            $this->stats = array(
                'get'        => 0,
                'get_multi'  => 0,
                'add'        => 0,
                'set'        => 0,
                'delete'     => 0,
                'miss'       => 0,
            );

            $memcached_servers = function_exists('get_memcached_servers') ? get_memcached_servers() : null;

            if (isset($memcached_servers)) {
                $buckets = $memcached_servers;
            } else {
                $buckets = array( '127.0.0.1' );
            }

            reset($buckets);
            if (is_int(key($buckets))) {
                $buckets = array( 'default' => $buckets );
            }

            foreach ($buckets as $bucket => $servers) {
                $this->mc[$bucket] = new Memcached('wpcache');
                $instances = array();
                foreach ($servers as $server) {
                    if (strpos($server, ':') !== false) {
                        list($node, $port) = explode(':', $server);
                    } else {
                        $node = $server;
                        $port = ini_get('memcache.default_port');
                    }
                    $port = intval($port);
                    if (!$port) {
                        $port = 11211;
                    }
                    $instances[] = array( $node, $port, 1 );
                }
                $this->mc[$bucket]->addServers($instances);
            }

            global $blog_id, $table_prefix;
            $this->global_prefix = '';
            $this->blog_prefix = '';
            if (function_exists('is_multisite')) {
                $this->global_prefix = (is_multisite() || defined('CUSTOM_USER_TABLE') && defined('CUSTOM_USER_META_TABLE')) ? '' : $table_prefix;
                $this->blog_prefix = (is_multisite() ? $blog_id : $table_prefix) . ':';
            }

            $this->cache_hits =& $this->stats['get'];
            $this->cache_misses =& $this->stats['miss'];
        }
    }
} else {
    // No Memcached
    if (function_exists('wp_using_ext_object_cache')) {
        // In 3.7+, we can handle this smoothly
        wp_using_ext_object_cache(false);
    } else {
        // In earlier versions, there isn't a clean bail-out method.
        wp_die('Memcached class not available.');
    }
}