文件缓存类，增加前缀清理功能

<?php
/**
 * 文件缓存类，增加前缀清理功能
 * @author WeakSun*/
namespace Think\Cache\Driver;

use Think\Cache;

defined('THINK_PATH') or exit();

/**
 * 文件类型缓存类
 */
class File extends Cache {

	/**
	 * 架构函数
	 * @access public
	 */
	public function __construct($options = array()) {
		if (!empty($options)) {
			$this->options = $options;
		}
		$this->options['temp'] = !empty($options['temp']) ? $options['temp'] : C('DATA_CACHE_PATH');
		$this->options['prefix'] = isset($options['prefix']) ? $options['prefix'] : C('DATA_CACHE_PREFIX');
		$this->options['expire'] = isset($options['expire']) ? $options['expire'] : C('DATA_CACHE_TIME');
		$this->options['length'] = isset($options['length']) ? $options['length'] : 0;
		$this->options['temp'] = rtrim($this->options['temp'], '\\/') . DIRECTORY_SEPARATOR;
		$this->init();
	}

	/**
	 * 初始化检查
	 * @access private
	 * @return boolean
	 */
	private function init() {
		// 创建应用缓存目录
		if (!is_dir($this->options['temp'])) {
			mkdir($this->options['temp']);
		}
	}

	/**
	 * 取得变量的存储文件名
	 * @access private
	 * @param string $name 缓存变量名
	 * @return string
	 */
	private function filename($name) {
		$name = md5(C('DATA_CACHE_KEY') . $name);
		if (C('DATA_CACHE_SUBDIR')) {
			// 使用子目录
			$dir = '';
			for ($i = 0; $i < C('DATA_PATH_LEVEL'); $i++) {
				$dir .= $name{$i} . DIRECTORY_SEPARATOR;
			}
			if (!is_dir($this->options['temp'] . $dir)) {
				mkdir($this->options['temp'] . $dir, 0755, true);
			}
			$filename = $dir . $this->options['prefix'] . $name . '.tmp';
		} else {
			$filename = $this->options['prefix'] . $name . '.tmp';
		}
		return $this->options['temp'] . $filename;
	}

	/**
	 * 读取缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @return mixed
	 */
	public function get($name) {
		$filename = $this->filename($name);
		if (!is_file($filename)) {
			return false;
		}
		N('cache_read', 1);
		$content = file_get_contents($filename);
		if (false !== $content) {
			$expire = (int) substr($content, 8, 12);
			if ($expire != 0 && time() > filemtime($filename) + $expire) {
				//缓存过期删除缓存文件
				unlink($filename);
				return false;
			}
			if (C('DATA_CACHE_CHECK')) {//开启数据校验
				$check = substr($content, 20, 32);
				$content = substr($content, 52);
				if ($check != md5($content)) {//校验错误
					return false;
				}
			} else {
				$content = substr($content, 20);
			}
			if (C('DATA_CACHE_COMPRESS') && function_exists('gzcompress')) {
				//启用数据压缩
				$content = gzuncompress($content);
			}
			$content = unserialize($content);
			return $content;
		} else {
			return false;
		}
	}

	/**
	 * 写入缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @param mixed $value  存储数据
	 * @param int $expire  有效时间 0为永久
	 * @return boolean
	 */
	public function set($name, $value, $expire = null) {
		N('cache_write', 1);
		if (is_null($expire)) {
			$expire = $this->options['expire'];
		}
		$filename = $this->filename($name);
		$data = serialize($value);
		if (C('DATA_CACHE_COMPRESS') && function_exists('gzcompress')) {
			//数据压缩
			$data = gzcompress($data, 3);
		}
		if (C('DATA_CACHE_CHECK')) {//开启数据校验
			$check = md5($data);
		} else {
			$check = '';
		}
		$data = "<?php\n//" . sprintf('%012d', $expire) . $check . $data;
		$result = file_put_contents($filename, $data);
		if ($result) {
			if ($this->options['length'] > 0) {
				// 记录缓存队列
				$this->queue($name);
			}
			clearstatcache();
			return true;
		} else {
			return false;
		}
	}

	/**
	 * 删除缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @return boolean
	 */
	public function rm($name) {
		if ($name == '%') {
			return $this->clearDir($this->options['temp'], true, $this->options['prefix']);
		} else {
			return $this->clearDir($this->filename($name));
		}
	}

	/**
	 * 清除缓存
	 * @access public
	 * @param string $name 缓存变量名
	 * @return boolean
	 */
	public function clear() {
		return $this->clearDir($this->options['temp']);
	}

	/**
	 * 清空目录
	 * @param string $dir 目录路径
	 * @param boolean $stay 是否保留目录
	 * @param string $pattern 文件筛选规则
	 * @return boolean
	 */
	protected function clearDir($dir, $stay = true, $pattern = null) {
		if (is_dir($dir)) {
			$dir = rtrim($dir, '\\/') . DIRECTORY_SEPARATOR;
			$list = array_merge(glob($dir . '*', GLOB_ONLYDIR), glob($dir . "{$pattern}*.*", GLOB_NOSORT));
			foreach ($list as $file) {
				$this->clearDir($file, !is_null($pattern), $pattern);
			}
			$stay || $stay = rmdir($dir);
		} elseif (is_file($dir)) {
			return unlink($dir);
		}
		return $stay;
	}

}