add Minify_Cache_XCache - xcache backend

based on APC and Memcache files

min/lib/Minify/Cache/XCache.php

@@ -0,0 +1,126 @@
+<?php
+/**
+ * Class Minify_Cache_XCache
+ *
+ * @link http://xcache.lighttpd.net/
+ * @package Minify
+ */
+
+/**
+ * XCache-based cache class for Minify
+ * {@see http://xcache.lighttpd.net/wiki/XcacheApi XCache API}
+ *
+ * <code>
+ * Minify::setCache(new Minify_Cache_XCache());
+ * </code>
+ *
+ * @package Minify
+ * @author Elan Ruusamäe <glen@delfi.ee>
+ **/
+class Minify_Cache_XCache {
+
+    /**
+     * Create a Minify_Cache_XCache object, to be passed to
+     * Minify::setCache().
+     *
+     * @param int $expire seconds until expiration (default = 0
+     * meaning the item will not get an expiration date)
+     */
+	public function __construct($expire = 0)
+    {
+        $this->_exp = $expire;
+    }
+
+    /**
+     * Write data to cache.
+     *
+     * @param string $id cache id
+     * @param string $data
+     * @return bool success
+     */
+    public function store($id, $data)
+    {
+        return xcache_set($id, "{$_SERVER['REQUEST_TIME']}|{$data}", $this->_exp);
+    }
+
+    /**
+     * Get the size of a cache entry
+     *
+     * @param string $id cache id
+     * @return int size in bytes
+     */
+    public function getSize($id)
+    {
+        if (! $this->_fetch($id)) {
+            return false;
+        }
+        return (function_exists('mb_strlen') && ((int)ini_get('mbstring.func_overload') & 2))
+            ? mb_strlen($this->_data, '8bit')
+            : strlen($this->_data);
+    }
+
+    /**
+     * Does a valid cache entry exist?
+     *
+     * @param string $id cache id
+     * @param int $srcMtime mtime of the original source file(s)
+     * @return bool exists
+     */
+    public function isValid($id, $srcMtime)
+    {
+        return ($this->_fetch($id) && ($this->_lm >= $srcMtime));
+    }
+
+    /**
+     * Send the cached content to output
+     *
+     * @param string $id cache id
+     */
+    public function display($id)
+    {
+        echo $this->_fetch($id)
+            ? $this->_data
+            : '';
+    }
+
+    /**
+     * Fetch the cached content
+     *
+     * @param string $id cache id
+     * @return string
+     */
+    public function fetch($id)
+    {
+        return $this->_fetch($id)
+            ? $this->_data
+            : '';
+    }
+
+    private $_exp = null;
+
+    // cache of most recently fetched id
+    private $_lm = null;
+    private $_data = null;
+    private $_id = null;
+
+    /**
+     * Fetch data and timestamp from xcache, store in instance
+     *
+     * @param string $id
+     * @return bool success
+     */
+    private function _fetch($id)
+    {
+        if ($this->_id === $id) {
+            return true;
+        }
+        $ret = xcache_get($id);
+        if (false === $ret) {
+            $this->_id = null;
+            return false;
+        }
+        list($this->_lm, $this->_data) = explode('|', $ret, 2);
+        $this->_id = $id;
+        return true;
+    }
+}