缓存类

<?php
class FileCache  
{  
     
    public $keyPrefix = '';  
    
    public $cachePath = '';  
   
    public $cacheFileSuffix = '.bin';  
    
    public $directoryLevel = 1;  
  
    public $gcProbability = 10;  
    
    public $fileMode;  
    
    public $dirMode = 0775;  
  
   
    function __construct()  
    {  
        $this->cachePath = HT::$cacheRoot.'htcache';  
    }  
  
    function FileCache()  
    {  
        $this->__construct();  
    }  
  
    
    public function set($key, $value, $duration = 0)  
    {
 //将内容存入文件中一般以字符串形式存储。要序列化。
serialize()就是将PHP中的变量如对象(object),数组(array)
等等的值序列化为字符串后存储起来
        $value = serialize([$value]);  
        $key = $this->buildKey($key);  
        return $this->setValue($key, $value, $duration);  
    }  
  

    public function get($key)  
    {  
        $key = $this->buildKey($key);  
        $value = $this->getValue($key);  
        if ($value === false) {  
            return $value;  
        } else {  
            $value = unserialize($value);  
        }  
        if (is_array($value)) {  
            return $value[0];  
        } else {  
            return false;  
        }  
    }  
  
 
    public function delete($key)  
    {  
        $key = $this->buildKey($key);  
  
        return $this->deleteValue($key);  
    }  
  

    public function buildKey($key)  
    {  
        if (is_string($key)) {
   //Returns TRUE if every character in text is either a letter or a digit
            $key = ctype_alnum($key) && mb_strlen($key, '8bit') <= 32 ? $key : md5($key);  
        } else {  
            $key = md5(json_encode($key, JSON_NUMERIC_CHECK));  
        }  
  
        return $this->keyPrefix . $key;  
    }  
  
  
    protected function setValue($key, $value, $duration)  
    {  
        $this->gc();  
        $cacheFile = $this->getCacheFile($key);  
        if ($this->directoryLevel > 0) {  
            @mkdir(dirname($cacheFile), $this->dirMode, true);  
        }  
        if (@file_put_contents($cacheFile, $value, LOCK_EX) !== false) {  
            if ($this->fileMode !== null) {
   //改变文件模式mode 不会被自动当成八进制数值，要确保正确操作，需要给 mode 前面加上 0
                @chmod($cacheFile, $this->fileMode);
            }  
            if ($duration <= 0) {  
                $duration = 31536000; // 1 year  
            }
       // touch — 设定文件的访问和修改时间
            return @touch($cacheFile, $duration + time());  
        } else {  
            $error = error_get_last();  
            HT::warning("Unable to write cache file '{$cacheFile}': {$error['message']}", __METHOD__);  
            return false;  
        }  
    }  
  

    protected function getValue($key)  
    {  
        $cacheFile = $this->getCacheFile($key);  
  
        if (@filemtime($cacheFile) > time()) {  
            $fp = @fopen($cacheFile, 'r');  
            if ($fp !== false) {  
                @flock($fp, LOCK_SH);  
                $cacheValue = @stream_get_contents($fp);  
                @flock($fp, LOCK_UN);  
                @fclose($fp);  
                return $cacheValue;  
            }  
        }  
  
        return false;  
    }  
  

    protected function deleteValue($key)  
    {  
        $cacheFile = $this->getCacheFile($key);  
  
        return @unlink($cacheFile);  
    }  
  
  
    protected function getCacheFile($key)  
    {  
        if ($this->directoryLevel > 0) {  
            $base = $this->cachePath;  
            for ($i = 0; $i < $this->directoryLevel; ++$i) {  
                if (($prefix = substr($key, $i + $i, 2)) !== false) {  
                    $base .= DIRECTORY_SEPARATOR . $prefix;  
                }  
            }  
  
            return $base . DIRECTORY_SEPARATOR . $key . $this->cacheFileSuffix;  
        } else {  
            return $this->cachePath . DIRECTORY_SEPARATOR . $key . $this->cacheFileSuffix;  
        }  
    }  
  
 
    public function gc($force = false, $expiredOnly = true)  
    {  
        if ($force || mt_rand(0, 1000000) < $this->gcProbability) {  
            $this->gcRecursive($this->cachePath, $expiredOnly);  
        }  
    }  
  
  
    protected function gcRecursive($path, $expiredOnly)  
    {  
        if (($handle = opendir($path)) !== false) {  
            while (($file = readdir($handle)) !== false) {
                //$file[0] . ..两种目录
                if ($file === '.' || $file==='..') {
                    continue;  
                }

                $fullPath = $path . DIRECTORY_SEPARATOR . $file;  
                if (is_dir($fullPath)) {  
                    $this->gcRecursive($fullPath, $expiredOnly);  
                    if (!$expiredOnly) {
                        //删除路径
                        if (!@rmdir($fullPath)) {  
                            $error = error_get_last();  
                            HT::warning("Unable to remove directory '{$fullPath}': {$error['message']}", __METHOD__);  
                        }  
                    }  
                } elseif (!$expiredOnly || $expiredOnly && @filemtime($fullPath) < time()) {  
                    if (!@unlink($fullPath)) {
                        //获取最近的一次错误；
                        $error = error_get_last();  
                        HT::warning("Unable to remove file '{$fullPath}': {$error['message']}", __METHOD__);  
                    }  
                }  
            }  
            closedir($handle);  
        }  
    }  
}  
?>