<?php
// +----------------------------------------------------------------------
// | ThinkPHP [ WE CAN DO IT JUST THINK IT ]
// +----------------------------------------------------------------------
// | Copyright (c) 2006-2014 http://thinkphp.cn All rights reserved.
// +----------------------------------------------------------------------
// | Licensed ( http://www.apache.org/licenses/LICENSE-2.0 )
// +----------------------------------------------------------------------
// | Author: liu21st <liu21st@gmail.com>
// +----------------------------------------------------------------------
namespace Think\Cache\Driver;

use Think\Cache;

/**
 * Shmop缓存驱动
 */
class Shmop extends Cache
{

    /**
     * 架构函数
     * @param array $options 缓存参数
     * @access public
     */
    public function __construct($options = array())
    {
        if (!extension_loaded('shmop')) {
            E(L('_NOT_SUPPORT_') . ':shmop');
        }
        if (!empty($options)) {
            $options = array(
                'size'    => C('SHARE_MEM_SIZE'),
                'temp'    => TEMP_PATH,
                'project' => 's',
                'length'  => 0,
            );
        }
        $this->options           = $options;
        $this->options['prefix'] = isset($options['prefix']) ? $options['prefix'] : C('DATA_CACHE_PREFIX');
        $this->options['length'] = isset($options['length']) ? $options['length'] : 0;
        $this->handler           = $this->_ftok($this->options['project']);
    }

    /**
     * 读取缓存
     * @access public
     * @param string $name 缓存变量名
     * @return mixed
     */
    public function get($name = false)
    {
        N('cache_read', 1);
        $id = shmop_open($this->handler, 'c', 0600, 0);
        if (false !== $id) {
            $ret = unserialize(shmop_read($id, 0, shmop_size($id)));
            shmop_close($id);

            if (false === $name) {
                return $ret;
            }
            $name = $this->options['prefix'] . $name;
            if (isset($ret[$name])) {
                $content = $ret[$name];
                if (C('DATA_CACHE_COMPRESS') && function_exists('gzcompress')) {
                    //启用数据压缩
                    $content = gzuncompress($content);
                }
                return $content;
            } else {
                return null;
            }
        } else {
            return false;
        }
    }

    /**
     * 写入缓存
     * @access public
     * @param string $name 缓存变量名
     * @param mixed $value  存储数据
     * @return boolean
     */
    public function set($name, $value)
    {
        N('cache_write', 1);
        $lh  = $this->_lock();
        $val = $this->get();
        if (!is_array($val)) {
            $val = array();
        }

        if (C('DATA_CACHE_COMPRESS') && function_exists('gzcompress')) {
            //数据压缩
            $value = gzcompress($value, 3);
        }
        $name       = $this->options['prefix'] . $name;
        $val[$name] = $value;
        $val        = serialize($val);
        if ($this->_write($val, $lh)) {
            if ($this->options['length'] > 0) {
                // 记录缓存队列
                $this->queue($name);
            }
            return true;
        }
        return false;
    }

    /**
     * 删除缓存
     * @access public
     * @param string $name 缓存变量名
     * @return boolean
     */
    public function rm($name)
    {
        $lh  = $this->_lock();
        $val = $this->get();
        if (!is_array($val)) {
            $val = array();
        }

        $name = $this->options['prefix'] . $name;
        unset($val[$name]);
        $val = serialize($val);
        return $this->_write($val, $lh);
    }

    /**
     * 生成IPC key
     * @access private
     * @param string $project 项目标识名
     * @return integer
     */
    private function _ftok($project)
    {
        if (function_exists('ftok')) {
            return ftok(__FILE__, $project);
        }

        if (strtoupper(PHP_OS) == 'WINNT') {
            $s = stat(__FILE__);
            return sprintf("%u", (($s['ino'] & 0xffff) | (($s['dev'] & 0xff) << 16) |
                (($project & 0xff) << 24)));
        } else {
            $filename = __FILE__ . (string) $project;
            for ($key = array(); sizeof($key) < strlen($filename); $key[] = ord(substr($filename, sizeof($key), 1)));
            return dechex(array_sum($key));
        }
    }

    /**
     * 写入操作
     * @access private
     * @param string $name 缓存变量名
     * @return integer|boolean
     */
    private function _write(&$val, &$lh)
    {
        $id = shmop_open($this->handler, 'c', 0600, $this->options['size']);
        if ($id) {
            $ret = shmop_write($id, $val, 0) == strlen($val);
            shmop_close($id);
            $this->_unlock($lh);
            return $ret;
        }
        $this->_unlock($lh);
        return false;
    }

    /**
     * 共享锁定
     * @access private
     * @param string $name 缓存变量名
     * @return boolean
     */
    private function _lock()
    {
        if (function_exists('sem_get')) {
            $fp = sem_get($this->handler, 1, 0600, 1);
            sem_acquire($fp);
        } else {
            $fp = fopen($this->options['temp'] . $this->options['prefix'] . md5($this->handler), 'w');
            flock($fp, LOCK_EX);
        }
        return $fp;
    }

    /**
     * 解除共享锁定
     * @access private
     * @param string $name 缓存变量名
     * @return boolean
     */
    private function _unlock(&$fp)
    {
        if (function_exists('sem_release')) {
            sem_release($fp);
        } else {
            fclose($fp);
        }
    }
}
