WordPress/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;
			}
		}

	}

	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;	
	}
}
?>