C time() vs php $_SERVER['REQUEST_TIME']

dogpatch · 10-05-2016, 11:10 AM

In a php script on my server, if i use $_SERVER['REQUEST_TIME'] to get the system clock time, and from that script execute a binary on the same server written in C which uses the time() function, will both functions always return the same clock value? That is to say, will the return value of time() in the C module always be within a few milliseconds of the $_SERVER['REQUEST_TIME'] value in the php script?

Am thinking perhaps one or the other function may be affected by an environment variable to adjust according to a time zone or daylight savings?

Guttorm · 10-05-2016, 12:39 PM

I think it can vary more if you have a slow posting/uploading client.

Quote:

'REQUEST_TIME'
The timestamp of the start of the request. Available since PHP 5.1.0.

This number is from the web server. If it's a slow POST, daylight time changes while transfering data, you can get very different numbers. You can use time() in PHP to get the time when the function is called.

dogpatch · 10-05-2016, 01:51 PM

Quote:

Originally Posted by Guttorm

'REQUEST_TIME'
The timestamp of the start of the request. Available since PHP 5.1.0.
.
.
.
You can use time() in PHP to get the time when the function is called.

So, 'the time when the function is called' is the time when the php script is loaded? And the 'start of the request' is when the script executes the particular line of code? Or vice-versa?

In this php script

Code:

<?php
.
.
some php code
.
.
.
$req_time = $_SERVER['REQUEST_TIME'];
$ptime = time();
.
.
some more php code
.
.
.
$ctime = exec(c_binary_which calls_time);
.
.
?>

$ptime might be a slightly smaller (earlier) time value than $req_time? And both might be smaller than $ctime?

keefaz · 10-05-2016, 02:52 PM

php time() and c time() get time in second, so if php code execution duration between both calls is less than one second (likely), $ptime and $ctime should have the same value, and same value as $req_time (no executed code between $req_time and $ptime settings)