php操作大文件数据的方法

@ini_set('memory_limit', '1G');
$fp = fopen('E:/code/share/log.txt', 'r');
if(fseek ($fp, 0, SEEK_END)!==-1){
    $maxPos = ftell($fp); 
    $last = 0;
    for($i=1; $i<$maxPos; $i++){
        fseek ($fp, $maxPos - $i, SEEK_SET);
        $data = fgets($fp);
        $cur = strlen(trim($data));
        if($last > 0 && $last > $cur){
            echo  $lastdata."----".$i."\n";
        }
        else{
            $lastdata = $data;
        }
        $last = $cur;
        if($i>50000) exit;
    }
}

fclose($fp);
exit("\n");