File records web page visits

The file records the number of web page visits and is normal when used under high concurrency;
$file = dirname(__FILE__).'/tongji.db';
//$data = unserialize(file_get_contents($file));
$fp=fopen($file,'r+');
$content='';

if (flock($fp,LOCK_EX)){
while (($buffer=fgets($fp,1024))!=false){
$content=$content.$buffer;
}
$data=unserialize($content);

//Set record key value
$total = 'total';
$month = date('Ym');
$today = date('Ymd');
$yesterday = date('Ymd',strtotime("-1 day"));
$tongji = array();
//Total visits increased
$tongji[$total] = $data[$total] + 1;
// Visits increased this month
$tongji[$month] = $data[$month] + 1;
// Increased visits today
$tongji[$today] = $data[$today] + 1;
//Keep visiting yesterday
$tongji[$yesterday] = $data[$yesterday];

//Save statistics
ftruncate($fp,0); // Truncate the file to the given length
rewind($fp); // Rewind the position of the file pointer
fwrite($fp, serialize($tongji));
flock($fp,LOCK_UN);
fclose($fp);

//Output data
$total = $tongji[$total];
$month = $tongji[$month];
$today = $tongji[$today];
$yesterday = $tongji[$yesterday]?$tongji[$yesterday]:0;
echo "document.write('President visited {$total}, this month {$month}, yesterday {$yesterday}, today {$today}');";

}