ThinkPHP 파일 업로드 시 중복 제거 방법

public function upload(){
        if(IS_GET){
            $this->display();
            exit;
        }
        $upload = new \Think\Upload();//      
        $upload->maxSize = 3145728;//      
        $upload->exts = array('csv');//        
        $upload->rootPath = './Public/Uploads/';//         
        $upload->savePath = '';//         
        $info = $upload->upload();
        if (!$info) {
            $this->error($upload->getError());
        }else{
        $this->import($upload->rootPath . $info['file']['savepath'].$info['file']['savename']);
        }
    }

 public function import($file){
        $encoding = detect_encoding($file);
        if ($encoding != 'UTF-8') {
            $contens = file_get_contents($file);
            $contens = mb_convert_encoding($contens, 'utf-8',$encoding);
            file_put_contents($file, $contens);
        }

        $fp = fopen($file, 'r');
        if ($fp) {
            $fields = array('no','name','sex');
            $model = M('student'); 
            $arrNo = $model->getField('no',true); 
            $arr = array();
            $filename = "./Public/Log/load.txt";
            $f = fopen($filename, 'w');
            
            while (($row = fgetcsv($fp,1000,","))!==false) {
            	$row = array_combine($fields, $row);
            	$name = $row['name'];
                $row['py']=SpGetPinyin($name);
                if (in_array($row['no'], $arrNo)) {
                   // echo $row['0']."    . 
";	
                	$data .= $row['no'] . "   \r
";
                }else{
                    $arr[] = $row;
                    $arrNo[] = $row['no'];
                	$data .= $row['no'] . "    \r
";
                }
                if (count($arr)==1000) {
                    $model->addAll($arr);
                    unset($arr);
                }
            }

            if (count($arr)>0) {
                $model->addAll($arr);
            }
            $this->show('    ！','utf8');
        }
        	$fwrite=fwrite($f,$data);

            $file_name = "load.txt";     //         
				$file_dir = "./Public/Log/";        //            
				//            
				if (! file_exists ( $file_dir . $file_name )) {    
				    echo "     ";    
				    exit ();    
				} else {    
				    //        
				    $file = fopen ( $file_dir . $file_name, "r" );    
				    //           
				    Header ( "Content-type: application/octet-stream" );    
				    Header ( "Accept-Ranges: bytes" );    
				    Header ( "Accept-Length: " . filesize ( $file_dir . $file_name ) );    
				    Header ( "Content-Disposition: attachment; filename=" . $file_name );    
				    //           
				    //                   
				    echo fread ( $file, filesize ( $file_dir . $file_name ) );    
				    fclose ( $file );    
				    // exit ();    
				}    
            
   }