【discuzX2】/source/class/class_core.php文件中核心高效缓存类discuz_memory分析

<?php
/**
 * Discuz 内存读写引擎
 * 支持 memcache, eAccelerator, XCache
 *
 * 使用的时候建议直接利用函数 memory()
 */
class discuz_memory
{
    var $config;
    var $extension = array();
    var $memory;
    var $prefix;
    var $type;
    var $keys;
    var $enable = false;

        /**
     * 确认当前系统支持的内存读写接口
     * @return discuz_memory
     */
    function discuz_memory() {//支持多种类型的缓存
        $this->extension['eaccelerator'] = function_exists('eaccelerator_get');
        $this->extension['apc'] = function_exists('apc_fetch');
        $this->extension['xcache'] = function_exists('xcache_get');
        $this->extension['memcache'] = extension_loaded('memcache');
    }

        /**
     * 依据config当中设置，初始化内存引擎
     * @param unknown_type $config
     */
    function init($config) {

        $this->config = $config;
        $this->prefix = empty($config['prefix']) ? substr(md5($_SERVER['HTTP_HOST']), 0, 6).'_' : $config['prefix'];
        $this->keys = array();

        if($this->extension['memcache'] && !empty($config['memcache']['server'])) {
            require_once libfile('class/memcache');
            $this->memory = new discuz_memcache();
            $this->memory->init($this->config['memcache']);
            if(!$this->memory->enable) {
                $this->memory = null;
            }
        }

        if(!is_object($this->memory) && $this->extension['eaccelerator'] && $this->config['eaccelerator']) {
            require_once libfile('class/eaccelerator');
            $this->memory = new discuz_eaccelerator();
            $this->memory->init(null);
        }

        if(!is_object($this->memory) && $this->extension['xcache'] && $this->config['xcache']) {
            require_once libfile('class/xcache');
            $this->memory = new discuz_xcache();
            $this->memory->init(null);
        }

        if(!is_object($this->memory) && $this->extension['apc'] && $this->config['apc']) {
            require_once libfile('class/apc');
            $this->memory = new discuz_apc();
            $this->memory->init(null);
        }

        if(is_object($this->memory)) {
            $this->enable = true;
            $this->type = str_replace('discuz_', '', get_class($this->memory));
            $this->keys = $this->get('memory_system_keys');
            $this->keys = !is_array($this->keys) ? array() : $this->keys;
        }

    }

        /**
     * 读取内存
     *
     * @param string $key
     * @return mix
     */
    function get($key) {
        $ret = null;
        if($this->enable) {
            $ret = $this->memory->get($this->_key($key));
            if(!is_array($ret)) {
                $ret = null;
                if(array_key_exists($key, $this->keys)) {
                    unset($this->keys[$key]);
                    $this->memory->set($this->_key('memory_system_keys'), array($this->keys));
                }
            } else {
                return $ret[0];
            }
        }
        return $ret;
    }

        /**
     * 写入内存
     *
     * @param string $key
     * @param array_string_number $value
     * @param int过期时间 $ttl
     * @return boolean
     */
    function set($key, $value, $ttl = 0) {

        $ret = null;
        if($this->enable) {
            $ret = $this->memory->set($this->_key($key), array($value), $ttl);
            if($ret) {
                $this->keys[$key] = true;
                $this->memory->set($this->_key('memory_system_keys'), array($this->keys));
            }
        }
        return $ret;
    }

        /**
     * 删除一个内存单元
     * @param 键值string $key
     * @return boolean
     */
    function rm($key) {
        $ret = null;
        if($this->enable) {
            $ret = $this->memory->rm($this->_key($key));
            unset($this->keys[$key]);
            $this->memory->set($this->_key('memory_system_keys'), array($this->keys));
        }
        return $ret;
    }

        /**
     * 清除当前使用的所有内存
     */
    function clear() {
        if($this->enable && is_array($this->keys)) {
            if(method_exists($this->memory, 'clear')) {
                $this->memory->clear();
            } else {
                $this->keys['memory_system_keys'] = true;
                foreach ($this->keys as $k => $v) {
                    $this->memory->rm($this->_key($k));
                }
            }
        }
        $this->keys = array();
        return true;
    }

        /**
     * 内部函数 追加键值前缀
     * @param string $str
     * @return boolean
     */
    function _key($str) {
        return ($this->prefix).$str;
    }

}
?>