root/memcached/trunk/object-cache.php

<?php

/*
Plugin Name: Memcached
Description: Memcached backend for the WP Object Cache.
Version: 2.0.1
Plugin URI: http://wordpress.org/extend/plugins/memcached/
Author: Ryan Boren, Denis de Bernardy

Install this file to wp-content/object-cache.php
*/

function wp_cache_add($key, $data, $flag = '', $expire = 0) {
        global $wp_object_cache;

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

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

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

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

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

function wp_cache_close() {
        global $wp_object_cache;

        return $wp_object_cache->close();
}

function wp_cache_delete($id, $flag = '') {
        global $wp_object_cache;

        return $wp_object_cache->delete($id, $flag);
}

function wp_cache_flush() {
        global $wp_object_cache;

        return $wp_object_cache->flush();
}

function wp_cache_get($id, $flag = '') {
        global $wp_object_cache;

        return $wp_object_cache->get($id, $flag);
}

function wp_cache_init() {
        global $wp_object_cache;

        $wp_object_cache = new WP_Object_Cache();
}

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

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

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

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

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 {
        var $global_groups = array ('users', 'userlogins', 'usermeta', 'site-options', 'site-lookup', 'blog-lookup', 'blog-details', 'rss');

        var $no_mc_groups = array( 'comment', 'counts' );

        var $autoload_groups = array ('options');

        var $cache = array();
        var $mc = array();
        var $stats = array();
        var $group_ops = array();

        var $cache_enabled = true;
        var $default_expiration = 0;

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

                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, false, $expire);

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

                return $result;
        }

        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);
        }

        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);
        }

        function incr($id, $n, $group) {
                $key = $this->key($id, $group);
                $mc =& $this->get_mc($group);

                return $mc->increment($key, $n);
        }

        function decr($id, $n, $group) {
                $key = $this->key($id, $group);
                $mc =& $this->get_mc($group);

                return $mc->decrement($key, $n);
        }

        function close() {

                foreach ( $this->mc as $bucket => $mc )
                        $mc->close();
        }

        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);

                @ ++$this->stats['delete'];
                $this->group_ops[$group][] = "delete $id";

                if ( false !== $result )
                        unset($this->cache[$key]);

                return $result; 
        }

        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;
        }

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

                if ( isset($this->cache[$key]) )
                        $value = $this->cache[$key];
                else if ( in_array($group, $this->no_mc_groups) )
                        $value = false;
                else
                        $value = $mc->get($key);

                @ ++$this->stats['get'];
                $this->group_ops[$group][] = "get $id";

                if ( NULL === $value )
                        $value = false;
                        
                $this->cache[$key] = $value;

                if ( 'checkthedatabaseplease' == $value )
                        $value = false;

                return $value;
        }

        function get_multi( $groups ) {
                /*
                format: $get['group-name'] = array( 'key1', 'key2' );
                */
                $return = array();
                foreach ( $groups as $group => $ids ) {
                        $mc =& $this->get_mc($group);
                        foreach ( $ids as $id ) {
                                $key = $this->key($id, $group);
                                if ( isset($this->cache[$key]) ) {
                                        $return[$key] = $this->cache[$key];
                                        continue;
                                } else if ( in_array($group, $this->no_mc_groups) ) {
                                        $return[$key] = false;
                                        continue;
                                } else {
                                        $return[$key] = $mc->get($key);
                                }
                        }
                        if ( $to_get ) {
                                $vals = $mc->get_multi( $to_get );
                                $return = array_merge( $return, $vals );
                        }
                }
                @ ++$this->stats['get_multi'];
                $this->group_ops[$group][] = "get_multi $id";
                $this->cache = array_merge( $this->cache, $return );
                return $return;
        }

        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+/', '', "$prefix$group:$key");
        }

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

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

                return $result;
        }

        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";
        }

        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 ( $this->debug )
                        var_dump($this->memcache_debug);
        }

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

        function failure_callback($host, $port) {
                //error_log("Connection failure for $host:$port\n", 3, '/tmp/memcached.txt');
        }

        function WP_Object_Cache() {
                global $memcached_servers;

                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 Memcache();
                        foreach ( $servers as $server  ) {
                                list ( $node, $port ) = explode(':', $server);
                                if ( !$port )
                                        $port = ini_get('memcache.default_port');
                                $port = intval($port);
                                if ( !$port )
                                        $port = 11211;
                                $this->mc[$bucket]->addServer($node, $port, true, 1, 1, 15, true, array($this, 'failure_callback'));
                                $this->mc[$bucket]->setCompressThreshold(20000, 0.2);
                        }
                }

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

                $this->cache_hits =& $this->stats['get'];
                $this->cache_misses =& $this->stats['add'];
        }
}
?>