root/tags/2.1/wp-includes/cache.php

<?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_close() {
    global $wp_object_cache;

    if ( ! isset($wp_object_cache) )
        return;
    return $wp_object_cache->save();
}

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() {
    $GLOBALS['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;

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

define('CACHE_SERIAL_HEADER', "<?php\n/*");
define('CACHE_SERIAL_FOOTER', "*/\n?".">");

class WP_Object_Cache {
    var $cache_dir;
    var $cache_enabled = false;
    var $expiration_time = 900;
    var $flock_filename = 'wp_object_cache.lock';
    var $mutex;
    var $cache = array ();
    var $dirty_objects = array ();
    var $non_existant_objects = array ();
    var $global_groups = array ('users', 'userlogins', 'usermeta');
    var $blog_id;
    var $cold_cache_hits = 0;
    var $warm_cache_hits = 0;
    var $cache_misses = 0;
    var $secret = '';

    function acquire_lock() {
        // Acquire a write lock.
        $this->mutex = @fopen($this->cache_dir.$this->flock_filename, 'w');
        if ( false == $this->mutex)
            return false;
        flock($this->mutex, LOCK_EX);
        return true;
    }

    function add($id, $data, $group = 'default', $expire = '') {
        if (empty ($group))
            $group = 'default';

        if (false !== $this->get($id, $group, false))
            return false;

        return $this->set($id, $data, $group, $expire);
    }

    function delete($id, $group = 'default', $force = false) {
        if (empty ($group))
            $group = 'default';

        if (!$force && false === $this->get($id, $group, false))
            return false;

        unset ($this->cache[$group][$id]);
        $this->non_existant_objects[$group][$id] = true;
        $this->dirty_objects[$group][] = $id;
        return true;
    }

    function flush() {
        if ( !$this->cache_enabled )
            return true;

        if ( ! $this->acquire_lock() )
            return false;

        $this->rm_cache_dir();
        $this->cache = array ();
        $this->dirty_objects = array ();
        $this->non_existant_objects = array ();

        $this->release_lock();

        return true;
    }

    function get($id, $group = 'default', $count_hits = true) {
        if (empty ($group))
            $group = 'default';

        if (isset ($this->cache[$group][$id])) {
            if ($count_hits)
                $this->warm_cache_hits += 1;
            return $this->cache[$group][$id];
        }

        if (isset ($this->non_existant_objects[$group][$id]))
            return false;

        //  If caching is not enabled, we have to fall back to pulling from the DB.
        if (!$this->cache_enabled) {
            if (!isset ($this->cache[$group]))
                $this->load_group_from_db($group);

            if (isset ($this->cache[$group][$id])) {
                $this->cold_cache_hits += 1;
                return $this->cache[$group][$id];
            }

            $this->non_existant_objects[$group][$id] = true;
            $this->cache_misses += 1;
            return false;
        }

        $cache_file = $this->cache_dir.$this->get_group_dir($group)."/".$this->hash($id).'.php';
        if (!file_exists($cache_file)) {
            $this->non_existant_objects[$group][$id] = true;
            $this->cache_misses += 1;
            return false;
        }

        // If the object has expired, remove it from the cache and return false to force
        // a refresh.
        $now = time();
        if ((filemtime($cache_file) + $this->expiration_time) <= $now) {
            $this->cache_misses += 1;
            $this->delete($id, $group, true);
            return false;
        }

        $this->cache[$group][$id] = unserialize(base64_decode(substr(@ file_get_contents($cache_file), strlen(CACHE_SERIAL_HEADER), -strlen(CACHE_SERIAL_FOOTER))));
        if (false === $this->cache[$group][$id])
            $this->cache[$group][$id] = '';

        $this->cold_cache_hits += 1;
        return $this->cache[$group][$id];
    }

    function get_group_dir($group) {
        if (false !== array_search($group, $this->global_groups))
            return $group;

        return "{$this->blog_id}/$group";
    }

    function hash($data) {
        if ( function_exists('hash_hmac') ) {
            return hash_hmac('md5', $data, $this->secret);
        } else {
            return md5($data . $this->secret);
        }
    }

    function load_group_from_db($group) {
        global $wpdb;

        if ('category' == $group) {
            $this->cache['category'] = array ();
            if ($dogs = $wpdb->get_results("SELECT * FROM $wpdb->categories")) {
                foreach ($dogs as $catt)
                    $this->cache['category'][$catt->cat_ID] = $catt;
            }
        } else
            if ('options' == $group) {
                $wpdb->hide_errors();
                if (!$options = $wpdb->get_results("SELECT option_name, option_value FROM $wpdb->options WHERE autoload = 'yes'")) {
                    $options = $wpdb->get_results("SELECT option_name, option_value FROM $wpdb->options");
                }
                $wpdb->show_errors();

                if ( ! $options )
                    return;

                foreach ($options as $option) {
                    $this->cache['options'][$option->option_name] = $option->option_value;
                }
            }
    }

    function make_group_dir($group, $perms) {
        $group_dir = $this->get_group_dir($group);
        $make_dir = '';
        foreach (split('/', $group_dir) as $subdir) {
            $make_dir .= "$subdir/";
            if (!file_exists($this->cache_dir.$make_dir)) {
                if (! @ mkdir($this->cache_dir.$make_dir))
                    break;
                @ chmod($this->cache_dir.$make_dir, $perms);
            }

            if (!file_exists($this->cache_dir.$make_dir."index.php")) {
                $file_perms = $perms & 0000666;
                @ touch($this->cache_dir.$make_dir."index.php");
                @ chmod($this->cache_dir.$make_dir."index.php", $file_perms);
            }
        }

        return $this->cache_dir."$group_dir/";
    }

    function rm_cache_dir() {
        $dir = $this->cache_dir;
        $dir = rtrim($dir, DIRECTORY_SEPARATOR);
        $top_dir = $dir;
        $stack = array($dir);
        $index = 0;

        while ($index < count($stack)) {
            # Get indexed directory from stack
            $dir = $stack[$index];

            $dh = @ opendir($dir);
            if (!$dh)
                return false;

            while (($file = @ readdir($dh)) !== false) {
                if ($file == '.' or $file == '..')
                    continue;

                if (@ is_dir($dir . DIRECTORY_SEPARATOR . $file))
                    $stack[] = $dir . DIRECTORY_SEPARATOR . $file;
                else if (@ is_file($dir . DIRECTORY_SEPARATOR . $file))
                    @ unlink($dir . DIRECTORY_SEPARATOR . $file);
            }

            $index++;
        }

        $stack = array_reverse($stack);  // Last added dirs are deepest
        foreach($stack as $dir) {
            if ( $dir != $top_dir)
                @ rmdir($dir);
        }

    }

    function release_lock() {
        // Release write lock.
        flock($this->mutex, LOCK_UN);
        fclose($this->mutex);
    }

    function replace($id, $data, $group = 'default', $expire = '') {
        if (empty ($group))
            $group = 'default';

        if (false === $this->get($id, $group, false))
            return false;

        return $this->set($id, $data, $group, $expire);
    }

    function set($id, $data, $group = 'default', $expire = '') {
        if (empty ($group))
            $group = 'default';

        if (NULL == $data)
            $data = '';

        $this->cache[$group][$id] = $data;
        unset ($this->non_existant_objects[$group][$id]);
        $this->dirty_objects[$group][] = $id;

        return true;
    }

    function save() {
        //$this->stats();

        if (!$this->cache_enabled)
            return true;

        if (empty ($this->dirty_objects))
            return true;

        // Give the new dirs the same perms as wp-content.
        $stat = stat(ABSPATH.'wp-content');
        $dir_perms = $stat['mode'] & 0007777; // Get the permission bits.
        $file_perms = $dir_perms & 0000666; // Remove execute bits for files.

        // Make the base cache dir.
        if (!file_exists($this->cache_dir)) {
            if (! @ mkdir($this->cache_dir))
                return false;
            @ chmod($this->cache_dir, $dir_perms);
        }

        if (!file_exists($this->cache_dir."index.php")) {
            @ touch($this->cache_dir."index.php");
            @ chmod($this->cache_dir."index.php", $file_perms);
        }

        if ( ! $this->acquire_lock() )
            return false;

        // Loop over dirty objects and save them.
        $errors = 0;
        foreach ($this->dirty_objects as $group => $ids) {
            $group_dir = $this->make_group_dir($group, $dir_perms);

            $ids = array_unique($ids);
            foreach ($ids as $id) {
                $cache_file = $group_dir.$this->hash($id).'.php';

                // Remove the cache file if the key is not set.
                if (!isset ($this->cache[$group][$id])) {
                    if (file_exists($cache_file))
                        @ unlink($cache_file);
                    continue;
                }

                $temp_file = tempnam($group_dir, 'tmp');
                $serial = CACHE_SERIAL_HEADER.base64_encode(serialize($this->cache[$group][$id])).CACHE_SERIAL_FOOTER;
                $fd = @fopen($temp_file, 'w');
                if ( false === $fd ) {
                    $errors++;
                    continue;
                }
                fputs($fd, $serial);
                fclose($fd);
                if (!@ rename($temp_file, $cache_file)) {
                    if (@ copy($temp_file, $cache_file))
                        @ unlink($temp_file);
                    else
                        $errors++;
                }
                @ chmod($cache_file, $file_perms);
            }
        }

        $this->dirty_objects = array();

        $this->release_lock();

        if ( $errors )
            return false;

        return true;
    }

    function stats() {
        echo "<p>";
        echo "<strong>Cold Cache Hits:</strong> {$this->cold_cache_hits}<br/>";
        echo "<strong>Warm Cache Hits:</strong> {$this->warm_cache_hits}<br/>";
        echo "<strong>Cache Misses:</strong> {$this->cache_misses}<br/>";
        echo "</p>";

        foreach ($this->cache as $group => $cache) {
            echo "<p>";
            echo "<strong>Group:</strong> $group<br/>";
            echo "<strong>Cache:</strong>";
            echo "<pre>";
            print_r($cache);
            echo "</pre>";
            if (isset ($this->dirty_objects[$group])) {
                echo "<strong>Dirty Objects:</strong>";
                echo "<pre>";
                print_r(array_unique($this->dirty_objects[$group]));
                echo "</pre>";
                echo "</p>";
            }
        }
    }

    function WP_Object_Cache() {
        return $this->__construct();
    }
    
    function __construct() {
        global $blog_id;

        register_shutdown_function(array(&$this, "__destruct"));

        if (defined('DISABLE_CACHE'))
            return;

        if ( ! defined('ENABLE_CACHE') )
            return;

        // Disable the persistent cache if safe_mode is on.
        if ( ini_get('safe_mode') && ! defined('ENABLE_CACHE') )
            return;

        if (defined('CACHE_PATH'))
            $this->cache_dir = CACHE_PATH;
        else
            // Using the correct separator eliminates some cache flush errors on Windows
            $this->cache_dir = ABSPATH.'wp-content'.DIRECTORY_SEPARATOR.'cache'.DIRECTORY_SEPARATOR;

        if (is_writable($this->cache_dir) && is_dir($this->cache_dir)) {
                $this->cache_enabled = true;
        } else {
            if (is_writable(ABSPATH.'wp-content')) {
                $this->cache_enabled = true;
            }
        }

        if (defined('CACHE_EXPIRATION_TIME'))
            $this->expiration_time = CACHE_EXPIRATION_TIME;

        if ( defined('WP_SECRET') )
            $this->secret = WP_SECRET;
        else
            $this->secret = DB_PASSWORD . DB_USER . DB_NAME . DB_HOST . ABSPATH;

        $this->blog_id = $this->hash($blog_id);
    }

    function __destruct() {
        $this->save();
        return true;    
    }
}
?>