<?php
/*
文件缓存类
基于secache修改
*/
class cpFileCache {

    private $idx_node_size = 40;
    private $data_base_pos = 262588; //40+20+24*16+16*16*16*16*4;
    private $schema_item_size = 24;
    private $header_padding = 20; //保留空间 放置php标记防止下载
    private $info_size = 20; //保留空间 4+16 maxsize|ver

    //40起 添加20字节保留区域
    private $idx_seq_pos = 40; //id 计数器节点地址
    private $dfile_cur_pos = 44; //id 计数器节点地址
    private $idx_free_pos = 48; //id 空闲链表入口地址

    private $idx_base_pos = 444; //40+20+24*16
    private $schema_struct = array('size','free','lru_head','lru_tail','hits','miss'); 
    private $ver = '$Rev: 3 $';

	public $config = array();

    public function __construct($config = array()) {
		$this->config = array(
								'DB_CACHE_PATH'	=> 'data/db_cache/', //缓存目录
								'DB_CACHE_CHECK' => 'false', //是否验证数据
								'DB_CACHE_FILE'	=> 'cachedata', //缓存的数据文件名
								'DB_CACHE_SIZE'	=> '15M', //预设的缓存大小
								'DB_CACHE_FLOCK' => 'true', //是否存在文件锁，设置为false，将模拟文件锁									
							);
		$this->config = array_merge($this->config, (array)$config);
		//检查缓存目录
		$this->_checkDir();
		$this->workat($this->config['DB_CACHE_PATH'] . $this->config['DB_CACHE_FILE']);
    }

	//读取缓存
    public function get($key){
		$key = md5($key);//设置索引值		
        if($this->fetch($key,$content)) {
            $expire  =  (int) substr($content, 0, 12);
            if($expire != -1 && time() >= $expire) {
                return false;
            }
            if($this->config['DB_CACHE_CHECK']) {
				//开启数据校验
                $check  =  substr($content,12, 32);
                $content   =  substr($content,44);
                if($check != md5($content)) {					
                    return false; //校验错误
                }
            } else {
            	$content   =  substr($content,12);
            }
            return unserialize($content);//解序列化数据
        } else {
            return false;
        }
    }
	
	//设置缓存
    public function set($key, $value, $expire = 1800){
		$key = md5($key);//设置索引值				
        $value = serialize($value);//将数据序列化
		$expire = ($expire == -1) ? $expire : (time() + $expire);//过期时间
		//是否开启数据校验
		$check = $this->config['DB_CACHE_CHECK'] ? md5($value) : '';
        $value    = sprintf('%012d', $expire).$check.$value;		
        return $this ->store($key, $value);//存储数据
    }
	
	//自增1
	public function inc($key, $value = 1){
		 return $this->set($key, intval($this->get($key)) + intval($value), -1);
    }
	
	//自减1
	public function des($key, $value = 1){
		 return $this->set($key, intval($this->get($key)) - intval($value), -1);
    }
	
	//删除
	public function del($key) {
		return $this->set($key,'',0);
	}
	
	//清空缓存
    public function clear() {
        return $this->_format(true);
    }
	
/***************下面是缓存算法的具体实现**********************/
	/*
	检查缓存目录
	*/
	 private function _checkDir(){
        // 如果缓存目录不存在或者不是目录，则创建缓存目录
        if ( (!file_exists($this->config['DB_CACHE_PATH'])) || (!is_dir($this->config['DB_CACHE_PATH'])) ) {
           //创建缓存目录
		    if (!@mkdir($this->config['DB_CACHE_PATH'], 0777, true)){
			    return false;
			 }
             
        }
		//检查缓存目录是否可写，不可写则修改它的属性
		if (!is_writable($this->config['DB_CACHE_PATH'])) {
			return	@chmod($this->config['DB_CACHE_PATH'], 0777);
		}
		return true;
    }
	
    public function workat($file)
	{

        $this->_file = $file.'.php';
        $this->_bsize_list = array(
            512=>10,
            3<<10=>10,
            8<<10=>10,
            20<<10=>4,
            30<<10=>2,
            50<<10=>2,
            80<<10=>2,
            96<<10=>2,
            128<<10=>2,
            224<<10=>2,
            256<<10=>2,
            512<<10=>1,
            1024<<10=>1,
        );

        $this->_node_struct = array(
            'next'=>array(0,'V'),
            'prev'=>array(4,'V'),
            'data'=>array(8,'V'),
            'size'=>array(12,'V'),
            'lru_right'=>array(16,'V'),
            'lru_left'=>array(20,'V'),
            'key'=>array(24,'H*'),
        );

        if(!file_exists($this->_file)){
            $this->create();
        }else{
            $this->_rs = fopen($this->_file,'rb+') or $this->trigger_error('Can\'t open the cachefile: '.realpath($this->_file),E_USER_ERROR);
            $this->_seek($this->header_padding);
            $info = unpack('V1max_size/a*ver',fread($this->_rs,$this->info_size));
            if($info['ver']!=$this->ver){
                $this->_format(true);
            }else{
                $this->max_size = $info['max_size'];
            }
        }

        $this->idx_node_base = $this->data_base_pos+$this->max_size;
        $this->_block_size_list = array_keys($this->_bsize_list);
        sort($this->_block_size_list);
        return true;
    }

    public function fetch($key,&$return){

        if($this->lock(false)){
            $locked = true;
        }

        if($this->search($key,$offset)){
            $info = $this->_get_node($offset);
            $schema_id = $this->_get_size_schema_id($info['size']);
            if($schema_id===false){
                if($locked) $this->unlock();
                return false;
            }

            $this->_seek($info['data']);
			//去除反序列化数据
           // $data = fread($this->_rs,$info['size']);
           // $return = unserialize($data);
			$return  = fread($this->_rs,$info['size']);
            if($return===false){
                if($locked) $this->unlock();
                return false;
            }

            if($locked){
                $this->_lru_push($schema_id,$info['offset']);
                $this->_set_schema($schema_id,'hits',$this->_get_schema($schema_id,'hits')+1);
                return $this->unlock();
            }else{
                return true;
            }
        }else{
            if($locked) $this->unlock();
            return false;
        }
    }
	
    public function store($key,$data){

        if($this->lock(true)){
            //save data
			//去除序列化数据
            //$data = serialize($value);
            $size = strlen($data);

            //get list_idx
            $has_key = $this->search($key,$list_idx_offset);
            $schema_id = $this->_get_size_schema_id($size);
            if($schema_id===false){
                $this->unlock();
                return false;
            }
            if($has_key){
                $hdseq = $list_idx_offset;

                $info = $this->_get_node($hdseq);
                if($schema_id == $this->_get_size_schema_id($info['size'])){
                    $dataoffset = $info['data'];
                }else{
                    //破掉原有lru
                    $this->_lru_delete($info);
                    if(!($dataoffset = $this->_dalloc($schema_id))){
                        $this->unlock();
                        return false;
                    }
                    $this->_free_dspace($info['size'],$info['data']);
                    $this->_set_node($hdseq,'lru_left',0);
                    $this->_set_node($hdseq,'lru_right',0);
                }

                $this->_set_node($hdseq,'size',$size);
                $this->_set_node($hdseq,'data',$dataoffset);
            }else{

                if(!($dataoffset = $this->_dalloc($schema_id))){
                    $this->unlock();
                    return false;
                }
                $hdseq = $this->_alloc_idx(array(
                    'next'=>0,
                    'prev'=>$list_idx_offset,
                    'data'=>$dataoffset,
                    'size'=>$size,
                    'lru_right'=>0,
                    'lru_left'=>0,
                    'key'=>$key,
                ));

                if($list_idx_offset>0){
                    $this->_set_node($list_idx_offset,'next',$hdseq);
                }else{
                    $this->_set_node_root($key,$hdseq);
                }
            }

            if($dataoffset>$this->max_size){
                $this->trigger_error('alloc datasize:'.$dataoffset,E_USER_WARNING);
                return false;
            }
            $this->_puts($dataoffset,$data);

            $this->_set_schema($schema_id,'miss',$this->_get_schema($schema_id,'miss')+1);

            $this->_lru_push($schema_id,$hdseq);
            $this->unlock();
            return true;
        }else{
            $this->trigger_error("Couldn't lock the file !",E_USER_WARNING);
            return false;
        }

    }

	//锁定文件
    protected function lock($is_block,$whatever=false){
      
	   if($this->config['DB_CACHE_FLOCK'])
	  	  return flock($this->_rs, $is_block?LOCK_EX:LOCK_EX+LOCK_NB);
  
        ignore_user_abort(true);
	    $support_usleep = version_compare(PHP_VERSION,5,'>=')?20:1;
        $lockfile = $this->_file . '.lck';

        if (file_exists($lockfile)) {
            if (time() - filemtime($lockfile) > 0){
               unlink($lockfile);
            }elseif(!$is_block){
                return false;
            }
        }

        $lock_ex = @fopen($lockfile, 'x');
        for ($i=0; ($lock_ex === false) && ($whatever || $i < 10); $i++) 
		{
           clearstatcache();
           if($support_usleep ==1){
               usleep(rand(9, 999));
           }else{
               sleep(1);
           }
           $lock_ex = @fopen($lockfile, 'x');
        }
        return ($lock_ex !== false);
    }

	//解除文件锁定
    protected function unlock()
	{
        if($this->config['DB_CACHE_FLOCK'])
	    	return flock($this->_rs, LOCK_UN);
		
	    ignore_user_abort(false);
        return @unlink($this->_file.'.lck');
    }
	
    protected function create()
	{
        $this->_rs = @fopen($this->_file,'wb+') or $this->trigger_error('创建缓存文件失败: '.$this->_file,E_USER_ERROR);;
        fseek($this->_rs,0);
        fputs($this->_rs,'<'.'?php exit()?'.'>');
        return $this->_format();
    }

    private function _puts($offset,$data){
        if($offset < $this->max_size*1.5){
            $this->_seek($offset);
            return fputs($this->_rs,$data);
        }else{
            $this->trigger_error('Offset over quota:'.$offset,E_USER_ERROR);
        }
    }

    private function _seek($offset){
        return fseek($this->_rs,$offset);
    }

    protected function delete($key,$pos=false){
        if($pos || $this->search($key,$pos)){
            if($info = $this->_get_node($pos)){
                //删除data区域
                if($info['prev']){
                    $this->_set_node($info['prev'],'next',$info['next']);
                    $this->_set_node($info['next'],'prev',$info['prev']);
                }else{ //改入口位置
                    $this->_set_node($info['next'],'prev',0);
                    $this->_set_node_root($key,$info['next']);
                }
                $this->_free_dspace($info['size'],$info['data']);
                $this->_lru_delete($info);
                $this->_free_node($pos);
                return $info['prev'];
            }
        }
        return false;
    }


    /**
     * search 
     * 查找指定的key
     * 如果找到节点则$pos=节点本身 返回true
     * 否则 $pos=树的末端 返回false
     * 
     * @param mixed $key 
     * @access public
     * @return void
     */
    protected function search($key,&$pos){
        return $this->_get_pos_by_key($this->_get_node_root($key),$key,$pos);
    }

    private function _get_size_schema_id($size){
        foreach($this->_block_size_list as $k=>$block_size){
            if($size <= $block_size){
                return $k;
            }
        }
        return false;
    }

    private function _parse_str_size($str_size,$default){
        if(preg_match('/^([0-9]+)\s*([gmk]|)$/i',$str_size,$match)){
            switch(strtolower($match[2])){
            case 'g':
                if($match[1]>1){
                    $this->trigger_error('Max cache size 1G',E_USER_ERROR);
                }
                $size = $match[1]<<30;
                break;
            case 'm':
                $size = $match[1]<<20;
                break;
            case 'k':
                $size = $match[1]<<10;
                break;
            default:
                $size = $match[1];
            }
            if($size<=0){
                $this->trigger_error('Error cache size '.$this->max_size,E_USER_ERROR);
                return false;
            }elseif($size<10485760){
                return 10485760;
            }else{
                return $size;
            }
        }else{
            return $default;
        }
    }


    private function _format($truncate=false){
        if($this->lock(true,true)){

            if($truncate){
                $this->_seek(0);
                ftruncate($this->_rs,$this->idx_node_base);
            }

            $this->max_size = $this->_parse_str_size($this->config['DB_CACHE_SIZE'],15728640); //default:15m
            $this->_puts($this->header_padding,pack('V1a*',$this->max_size,$this->ver));

            ksort($this->_bsize_list);
            $ds_offset = $this->data_base_pos;
            $i=0;
            foreach($this->_bsize_list as $size=>$count){

                //将预分配的空间注册到free链表里
                $count *= min(3,floor($this->max_size/10485760));
                $next_free_node = 0;
                for($j=0;$j<$count;$j++){
                    $this->_puts($ds_offset,pack('V',$next_free_node));
                    $next_free_node = $ds_offset;
                    $ds_offset+=intval($size);
                }

                $code = pack(str_repeat('V1',count($this->schema_struct)),$size,$next_free_node,0,0,0,0);

                $this->_puts(60+$i*$this->schema_item_size,$code);
                $i++;
            }
            $this->_set_dcur_pos($ds_offset);

            $this->_puts($this->idx_base_pos,str_repeat("\0",262144));
            $this->_puts($this->idx_seq_pos,pack('V',1));
            $this->unlock();
            return true;
        }else{
            $this->trigger_error("Couldn't lock the file !",E_USER_ERROR);
            return false;
        }
    }

    private function _get_node_root($key){
        $this->_seek(hexdec(substr($key,0,4))*4+$this->idx_base_pos);
        $a= fread($this->_rs,4);
        list(,$offset) = unpack('V',$a);
        return $offset;
    }

    private function _set_node_root($key,$value){
        return $this->_puts(hexdec(substr($key,0,4))*4+$this->idx_base_pos,pack('V',$value));
    }

    private function _set_node($pos,$key,$value){

        if(!$pos){
            return false;
        }

        if(isset($this->_node_struct[$key])){
            return $this->_puts($pos*$this->idx_node_size+$this->idx_node_base+$this->_node_struct[$key][0],pack($this->_node_struct[$key][1],$value));
        }else{
            return false;
        }
    }

    private function _get_pos_by_key($offset,$key,&$pos){
        if(!$offset){
            $pos = 0;
            return false;
        }

        $info = $this->_get_node($offset);

        if($info['key']==$key){
            $pos = $info['offset'];
            return true;
        }elseif($info['next'] && $info['next']!=$offset){
            return $this->_get_pos_by_key($info['next'],$key,$pos);
        }else{
            $pos = $offset;
            return false;
        }
    }

    private function _lru_delete($info){

        if($info['lru_right']){
            $this->_set_node($info['lru_right'],'lru_left',$info['lru_left']);
        }else{
            $this->_set_schema($this->_get_size_schema_id($info['size']),'lru_tail',$info['lru_left']);
        }

        if($info['lru_left']){
            $this->_set_node($info['lru_left'],'lru_right',$info['lru_right']);
        }else{
            $this->_set_schema($this->_get_size_schema_id($info['size']),'lru_head',$info['lru_right']);
        }

        return true;
    }

    private function _lru_push($schema_id,$offset){
        $lru_head = $this->_get_schema($schema_id,'lru_head');
        $lru_tail = $this->_get_schema($schema_id,'lru_tail');

        if((!$offset) || ($lru_head==$offset))return;

        $info = $this->_get_node($offset);

        $this->_set_node($info['lru_right'],'lru_left',$info['lru_left']);
        $this->_set_node($info['lru_left'],'lru_right',$info['lru_right']);

        $this->_set_node($offset,'lru_right',$lru_head);
        $this->_set_node($offset,'lru_left',0);

        $this->_set_node($lru_head,'lru_left',$offset);
        $this->_set_schema($schema_id,'lru_head',$offset);

        if($lru_tail==0){
            $this->_set_schema($schema_id,'lru_tail',$offset);
        }elseif($lru_tail==$offset && $info['lru_left']){
            $this->_set_schema($schema_id,'lru_tail',$info['lru_left']);
        }
        return true;
    }

    private function _get_node($offset){
        $this->_seek($offset*$this->idx_node_size + $this->idx_node_base);
        $info = unpack('V1next/V1prev/V1data/V1size/V1lru_right/V1lru_left/H*key',fread($this->_rs,$this->idx_node_size));
        $info['offset'] = $offset;
        return $info;
    }

    private function _lru_pop($schema_id){
        if($node = $this->_get_schema($schema_id,'lru_tail')){
            $info = $this->_get_node($node);
            if(!$info['data']){
                return false;
            }
            $this->delete($info['key'],$info['offset']);
            if(!$this->_get_schema($schema_id,'free')){
                $this->trigger_error('pop lru,But nothing free...',E_USER_ERROR);
            }
            return $info;
        }else{
            return false;
        }
    }

    private function _dalloc($schema_id,$lru_freed=false){

        if($free = $this->_get_schema($schema_id,'free')){ //如果lru里有链表
            $this->_seek($free);
            list(,$next) = unpack('V',fread($this->_rs,4));
            $this->_set_schema($schema_id,'free',$next);
            return $free;
        }elseif($lru_freed){
            $this->trigger_error('Bat lru poped freesize',E_USER_ERROR);
            return false;
        }else{
            $ds_offset = $this->_get_dcur_pos();
            $size = $this->_get_schema($schema_id,'size');

            if($size+$ds_offset > $this->max_size){
                if($info = $this->_lru_pop($schema_id)){
                    return $this->_dalloc($schema_id,$info);
                }else{
                    $this->trigger_error('Can\'t alloc dataspace',E_USER_ERROR);
                    return false;
                }
            }else{
                $this->_set_dcur_pos($ds_offset+$size);
                return $ds_offset;
            }
        }
    }

    private function _get_dcur_pos(){
        $this->_seek($this->dfile_cur_pos);
        list(,$ds_offset) = unpack('V',fread($this->_rs,4));
        return $ds_offset;
    }
    private function _set_dcur_pos($pos){
        return $this->_puts($this->dfile_cur_pos,pack('V',$pos));
    }

    private function _free_dspace($size,$pos){

        if($pos>$this->max_size){
            $this->trigger_error('free dspace over quota:'.$pos,E_USER_ERROR);
            return false;
        }

        $schema_id = $this->_get_size_schema_id($size);
        if($free = $this->_get_schema($schema_id,'free')){
            $this->_puts($free,pack('V1',$pos));
        }else{
            $this->_set_schema($schema_id,'free',$pos);
        }
        $this->_puts($pos,pack('V1',0));
    }

    private function _dfollow($pos,&$c){
        $c++;
        $this->_seek($pos);
        list(,$next) = unpack('V1',fread($this->_rs,4));
        if($next){
            return $this->_dfollow($next,$c);
        }else{
            return $pos;
        }
    }

    private function _free_node($pos){
        $this->_seek($this->idx_free_pos);
        list(,$prev_free_node) = unpack('V',fread($this->_rs,4));
        $this->_puts($pos*$this->idx_node_size+$this->idx_node_base,pack('V',$prev_free_node).str_repeat("\0",$this->idx_node_size-4));
        return $this->_puts($this->idx_free_pos,pack('V',$pos));
    }

    private function _alloc_idx($data){
        $this->_seek($this->idx_free_pos);
        list(,$list_pos) = unpack('V',fread($this->_rs,4));
        if($list_pos){

            $this->_seek($list_pos*$this->idx_node_size+$this->idx_node_base);
            list(,$prev_free_node) = unpack('V',fread($this->_rs,4));
            $this->_puts($this->idx_free_pos,pack('V',$prev_free_node));

        }else{
            $this->_seek($this->idx_seq_pos);
            list(,$list_pos) = unpack('V',fread($this->_rs,4));
            $this->_puts($this->idx_seq_pos,pack('V',$list_pos+1));
        }
        return $this->_create_node($list_pos,$data);
    }

    private function _create_node($pos,$data){
        $this->_puts($pos*$this->idx_node_size + $this->idx_node_base
            ,pack('V1V1V1V1V1V1H*',$data['next'],$data['prev'],$data['data'],$data['size'],$data['lru_right'],$data['lru_left'],$data['key']));
        return $pos;
    }

    private function _set_schema($schema_id,$key,$value){
        $info = array_flip($this->schema_struct);
        return $this->_puts(60+$schema_id*$this->schema_item_size + $info[$key]*4,pack('V',$value));
    }

    private function _get_schema($id,$key){
        $info = array_flip($this->schema_struct);

        $this->_seek(60+$id*$this->schema_item_size);
        unpack('V1'.implode('/V1',$this->schema_struct),fread($this->_rs,$this->schema_item_size));

        $this->_seek(60+$id*$this->schema_item_size + $info[$key]*4);
        list(,$value) =unpack('V',fread($this->_rs,4));
        return $value;
    }

    private function _all_schemas(){
        $schema = array();
        for($i=0;$i<16;$i++){
            $this->_seek(60+$i*$this->schema_item_size);
            $info = unpack('V1'.implode('/V1',$this->schema_struct),fread($this->_rs,$this->schema_item_size));
            if($info['size']){
                $info['id'] = $i;
                $schema[$i] = $info;
            }else{
                return $schema;
            }
        }
    }

    protected function schemaStatus(){
        $return = array();
        foreach($this->_all_schemas() as $k=>$schemaItem){
            if($schemaItem['free']){
                $this->_dfollow($schemaItem['free'],$schemaItem['freecount']);
            }
            $return[] = $schemaItem;
        }
        return $return;
    }

    protected function status(&$curBytes,&$totalBytes){
        $totalBytes = $curBytes = 0;
        $hits = $miss = 0;

        $schemaStatus = $this->schemaStatus();
        $totalBytes = $this->max_size;
        $freeBytes = $this->max_size - $this->_get_dcur_pos();

        foreach($schemaStatus as $schema){
            $freeBytes+=$schema['freecount']*$schema['size'];
            $miss += $schema['miss'];
            $hits += $schema['hits'];
        }
        $curBytes = $totalBytes-$freeBytes;

        $return[] = array('name'=>'缓存命中','value'=>$hits);
        $return[] = array('name'=>'缓存未命中','value'=>$miss);
        return $return;
    }

    protected function trigger_error($errstr,$errno){
		throw new Exception($errstr);//输出错误信息
    }
}