root/memcached/trunk/object-cache.php

<?php

/*
Name: Memcached
Description: Memcached backend for the WP Object Cache.
Version: 2.0
URI: http://dev.wp-plugins.org/browser/memcached/
Author: Ryan Boren


Install this file to wp-content/object-cache.php along with
memcached-client.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 true;
}

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;
        }

        $mc =& $this->get_mc($group);
        $expire = ($expire == 0) ? $this->default_expiration : $expire;
        $result = $mc->add($key, $data, false, $expire);
        @ ++$this->stats['add'];
        $this->group_ops[$group][] = "add $id";

        if ( false !== $result )
            $this->cache[$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() {
        return true;
    }

    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) {    
        global $blog_id;

        if ( empty($group) )
            $group = 'default';

        if (false !== array_search($group, $this->global_groups))
            $prefix = '';
        else
            $prefix = $blog_id . ':';

        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('default' => array('127.0.0.1:11211'));

        foreach ( $buckets as $bucket => $servers) {
            $this->mc[$bucket] = new Memcache();
            foreach ( $servers as $server  ) {
                list ( $node, $port ) = explode(':', $server);
                $this->mc[$bucket]->addServer($node, $port, true, 1, 1, 15, true, array($this, 'failure_callback'));
                $this->mc[$bucket]->setCompressThreshold(20000, 0.2);
            }
        }
    }
}
?>