Detailed explanation of PHP data compression, encryption and decryption (pack, unpack)

<?php 
//存储整数1234567890 
file_put_contents("test.txt", 1234567890);

<?php 
print_r(unpack("i", file_get_contents("test.txt")));

<?php 
file_put_contents("test.txt", "7-110-abcdefg-117");

<?php 
file_put_contents("test.txt", pack("i2a7i1", 7, 110, "abcdefg", 117));

<?php 
error_reporting(E_ALL); 
 
class fileCacheException extends Exception{ 
 
} 
 
//Key-Value型文件存储 
class fileCache{ 
   private $_file_header_size = 14; 
   private $_file_index_name; 
   private $_file_data_name; 
   private $_file_index;//索引文件句柄 
   private $_file_data;//数据文件句柄 
   private $_node_struct;//索引结点结构体 
   private $_inx_node_size = 36;//索引结点大小 
 
   public function __construct($file_index="filecache_index.dat", $file_data="filecache_data.dat"){ 
     $this->_node_struct = array( 
        &#39;next&#39;=>array(1, &#39;V&#39;), 
        &#39;prev&#39;=>array(1, &#39;V&#39;), 
       &#39;data_offset&#39;=>array(1,&#39;V&#39;),//数据存储起始位置 
       &#39;data_size&#39;=>array(1,&#39;V&#39;),//数据长度 
       &#39;ref_count&#39;=>array(1,&#39;V&#39;),//引用此处，模仿PHP的引用计数销毁模式 
       &#39;key&#39;=>array(16,&#39;H*&#39;),//存储KEY 
     ); 
 
     $this->_file_index_name = $file_index; 
     $this->_file_data_name = $file_data; 
 
     if(!file_exists($this->_file_index_name)){ 
        $this->_create_index(); 
     }else{ 
        $this->_file_index = fopen($this->_file_index_name, "rb+"); 
     } 
 
     if(!file_exists($this->_file_data_name)){ 
        $this->_create_data(); 
     }else{ 
        $this->_file_data = fopen($this->_file_data_name, "rb+");//二进制存储需要使用b 
     } 
   } 
 
   //创建索引文件 
   private function _create_index(){ 
     $this->_file_index = fopen($this->_file_index_name, "wb+");//二进制存储需要使用b 
     if(!$this->_file_index)  
        throw new fileCacheException("Could&#39;t open index file:".$this->_file_index_name); 
 
     $this->_index_puts(0, &#39;<&#39;.&#39;?php exit()?&#39;.&#39;>&#39;);//定位文件流至起始位置0, 放置php标记防止下载 
     $this->_index_puts($this->_file_header_size, pack("V1", 0)); 
   } 
 
 
   //创建存储文件 
   private function _create_data(){ 
     $this->_file_data = fopen($this->_file_data_name, "wb+");//二进制存储需要使用b 
     if(!$this->_file_index)  
        throw new fileCacheException("Could&#39;t open index file:".$this->_file_data_name); 
 
     $this->_data_puts(0, &#39;<&#39;.&#39;?php exit()?&#39;.&#39;>&#39;);//定位文件流至起始位置0, 放置php标记防止下载 
   } 
 
   private function _index_puts($offset, $data, $length=false){ 
     fseek($this->_file_index, $offset); 
 
     if($length) 
     fputs($this->_file_index, $data, $length); 
     else 
     fputs($this->_file_index, $data); 
   } 
 
   private function _data_puts($offset, $data, $length=false){ 
     fseek($this->_file_data, $offset); 
     if($length) 
     fputs($this->_file_data, $data, $length); 
     else 
     fputs($this->_file_data, $data); 
   } 
 
   /** 
   * 文件锁 
   * @param $is_block 是否独占、阻塞锁 
   */ 
   private function _lock($file_res, $is_block=true){ 
     flock($file_res, $is_block ? LOCK_EX : LOCK_EX|LOCK_NB); 
   } 
 
   private function _unlock($file_res){ 
     flock($file_res, LOCK_UN); 
   } 
 
   public function add($key, $value){ 
     $key = md5($key); 
     $value = serialize($value); 
     $this->_lock($this->_file_index, true); 
     $this->_lock($this->_file_data, true); 
 
     fseek($this->_file_index, $this->_file_header_size); 
 
     list(, $index_count) = unpack(&#39;V1&#39;, fread($this->_file_index, 4)); 
 
     $data_size = filesize($this->_file_data_name); 
 
     fseek($this->_file_data, $data_size); 
 
     $value_size = strlen($value); 
 
     $this->_data_puts(filesize($this->_file_data_name), $value); 
 
     $node_data =  
     pack("V1V1V1V1V1H32", ($index_count==0) ? 0 : $index_count*$this->_inx_node_size, 0, filesize($this->_file_data_name), strlen($value), 0, $key); 
 
     $index_count++; 
 
     $this->_index_puts($this->_file_header_size, $index_count, 4); 
 
     $this->_index_puts($this->get_new_node_pos($index_count), $node_data); 
 
     $this->_unlock($this->_file_data); 
     $this->_unlock($this->_file_index); 
   } 
 
   public function get_new_node_pos($index_count){ 
     return $this->_file_header_size + 4 + $this->_inx_node_size * ($index_count-1); 
   } 
 
   public function get_node($key){ 
     $key = md5($key); 
     fseek($this->_file_index, $this->_file_header_size); 
     $index_count = fread($this->_file_index, 4); 
 
     if($index_count>0) { 
        for ($i=0; $i < $index_count ; $i++) {  
          fseek($this->_file_index, $this->_file_header_size + 4 + $this->_inx_node_size * $i); 
          $data = fread($this->_file_index, $this->_inx_node_size); 
          $node = unpack("V1next/V1prev/V1data_offset/V1data_size/V1ref_count/H32key", $data); 
 
          if($key == $node[&#39;key&#39;]){ 
             return $node; 
          } 
        } 
     }else{ 
        return null; 
     } 
   } 
 
   public function get_data($offset, $length){ 
     fseek($this->_file_data, $offset); 
     return unserialize(fread($this->_file_data, $length)); 
   } 
} 
 
//使用方法 
$cache = new fileCache(); 
$cache->add(&#39;abcdefg&#39; , &#39;testabc&#39;); 
$data = $cache->get_node(&#39;abcdefg&#39;); 
print_r($data); 
echo $cache->get_data($data[&#39;data_offset&#39;], $data[&#39;data_size&#39;]);

$LOGIN = array( 
   'COMMAND'=>array('a30', 'LOGIN'), 
   'DATA'=>array('a30', 'HELLO') 
); 
 
$LOGOUT = array( 
   'COMMAND'=>array('a30', 'LOGOUT'), 
   'DATA'=>array('a30', 'GOOD BYE') 
); 
 
$LOGIN_SUCCESS = array( 
   'COMMAND'=>array('a30', 'LOGIN_SUCCESS'), 
   'DATA'=>array('V1', 1) 
); 
 
$LOGOUT_SUCCESS = array( 
   'COMMAND'=>array('a30', 'LOGIN_SUCCESS'), 
   'DATA'=>array('V1', time()) 
);