php文件缓存类

<?php
/**
 * 文件缓存类
 * @author flynetcn
 */
class FileCache
{
    const CACHE_DIR = '/tmp/cache';
    private $dir;
    private $expire = 300;

    /**
     * @param $strDir 缓存子目录(方便清cache)
     */
    function __construct($strDir='')
    {
        if ($strDir) {
            $this->dir = self::CACHE_DIR.'/'.$strDir;
        }
    }

    private function getFileName($strKey)
    {
        return $this->dir.'/'.$strKey;
    }

    public function setExpire($intSecondNum)
    {
        if ($intSecondNum<10 || !is_int($intSecondNum)) {
            return false;
        }
        $this->expire = $intSecondNum;
        return true;
    }

    public function getExpire()
    {
        return $this->expire;
    }

    public function get($strKey)
    {
        $strFileName = $this->getFileName($strKey);
        if (!@file_exists($strFileName)) {
            return false;
        }
        if (filemtime($strFileName) < (time()-$this->expire)) {
            return false;
        }
        $intFileSize = filesize($strFileName);
        if ($intFileSize == 0) {
            return false;
        }
        if (!$fp = @fopen($strFileName, 'rb')) {
            return false;
        }
        flock($fp, LOCK_SH);
        $cacheData = unserialize(fread($fp, $intFileSize));
        flock($fp, LOCK_UN);
        fclose($fp);
        return $cacheData;
    }

    public function set($strKey, $cacheData)
    {
        if (!is_dir($this->dir)) {
            if (!@mkdir($this->dir, 0755, true)) {
                trigger_error("mkdir({$this->dir}, 0755, true) failed", E_USER_ERROR);
                return false;
            }
        }
        $strFileName = $this->getFileName($strKey);
        if (@file_exists($strFileName)) {
            $intMtime = filemtime($strFileName);
        } else {
            $intMtime = 0;
        }
        if (!$fp = fopen($strFileName,'wb')) {
            return false;
        }
        if (!flock($fp, LOCK_EX+LOCK_NB)) {
            fclose($fp);
            return false;
        }
        if (time() - $intMtime < 1) {
            flock($fp, LOCK_UN);
            fclose($fp);
            return false;
        }
        fseek($fp, 0);
        ftruncate($fp, 0);
        fwrite($fp, serialize($cacheData));
        flock($fp, LOCK_UN);
        fclose($fp);
        @chmod($strFileName, 0755);
        return true;
    }
}