Benchmark: $gentime vs. filemtime (Filecache)

/*
// version 3
// run: 0.243602633478
// run: 0.245651497837 10 secs
// run: 0.233414025306 30 secs
// fastest run: 0.114813804626
$data = array();
$h = fopen($filename, 'a');
if (flock($h, LOCK_EX | LOCK_NB)) {
$data = @unserialize(file_get_contents($filename));
}
if (!$data || filemtime($filename) + 2 < $now) {
// read data (db query...)
$data = array(
'id' => 1111,
0 => 'long text',
1 => 'long text',
2 => 'long text with quotes',
);
// write cache file
ftruncate($h, 0);
fwrite($h, serialize($data));
umask(0000);
chmod($filename, 0644);
}
flock($h, LOCK_UN);
fclose($h);
// only for the benchmark to avoid caching
clearstatcache();
*/
/*
// version 4
// run: 0.188958084584
// run: 0.185067784788
// fastest run: 0.0628659725189
// cache file will be created if didn't existed or refreshed all 2 seconds
// we removed file_exists() as we expect in 99% of all cases that the file is
// existing and if not, file_get_contents() does the same for us
if (!($data = @file_get_contents($filename)) || ($data = @unserialize($data)) === false || filemtime($filename) + 2 < $now) {
// read data (db query...)
$data = array(
'id' => 1111,
0 => 'long text',
1 => 'long text',
2 => 'long text with quotes',
);
// write cache file
// we do not need to lock, as unserialize results false if data set is corrupt
$h = @fopen($filename, 'w');
@fwrite($h, serialize($data));
@fclose($h);
@umask(0000);
@chmod($filename, 0644);
}
// only for the benchmark to avoid caching
clearstatcache();
*/
/*
// version 5
// run: 0.0989973068235
// run: 0.0999602222446
// fastest run: 0.0978970527649
// our script results more than 100 hits per second, so we add a random
// switch to reduce usage of filemtime()
// if you run this script on a website, you have to count your daily impressions
// and decide how much filemtime() requests are needed to find the balance between
// cache actuality and interval. f.e.: you have a birthday data cache and you want
// to refresh it every 24 hours. your website results 100.000 impressions per day.
// i would choose 100 as a good random factor as there are 1.000 impressions left
// to refresh the cache. one of them should hit between 00:00 and 00:59 to result
// actual birthday data on the website (with factor 100 apprx. 42 impressions per
// hour can hit our random factor)
if (!($data = @file_get_contents($filename)) || ($data = @unserialize($data)) === false || (rand(0, 100) == 100 && filemtime($filename) + 2 < $now)) {
// read data (db query...)
$data = array(
'id' => 1111,
0 => 'long text',
1 => 'long text',
2 => 'long text with quotes',
);
// write cache file
// we do not need to lock, as unserialize results false if data set is corrupt
$h = @fopen($filename, 'w');
@fwrite($h, serialize($data));
@fclose($h);
@umask(0000);
@chmod($filename, 0644);
}
if (isset($h)) {
// only for the benchmark to avoid caching
clearstatcache();
}
*/