file download time log

Question

Is there any way to log (record) the time it takes to download a file from a web server via the browser? The file is written on the HDD and the environment is LAMP.

Thanks.

Answer 1

One way would be to proxy the download via a script (can be achieved easily with mod_rewrite). This means that you need to do all the work like mapping extensions into their corresponding mime-types (for the Content-Type header). Try downloading a file from your browser, and take a look at the headers it sends; you need to mimic those. You can use eg. web-sniffer.net to inspect the headers.

Answer 2

I don't think PHP would have access to this kind of information. I'm not sure if Apache will tell you either, or whether the method below will also time just until the file got dumped into the transmit buffer, but I would suggest you try this:

Define a custom log in which you include the "%D" directive, this gives you "The time taken to serve the request, in microseconds."

Answer 3

Sure there is. You will have to either use mod_rewrite to let Apache know the file is to be served by PHP (ask for more instructions if this is your case) or just use a PHP script to fetch the file like this:

http://youserver.com/download.php?filename=mypicture.jpeg

And then you can can have download.php like this:

<?php
// gets the starting time
$time_start = microtime(true);

// WATCHOUT! THIS IS NOT SECURE! EXAMPLE ONLY.
#$filename = $_GET['filename'];

// gets the intro.mp3 file and outputs it to the user
$filename = "intro.mp3";
header('Content-type: audio/mpeg');
header('Content-Length: '.filesize($filename));
header('Content-Disposition: attachment; filename="intro.mp3"');
readfile($filename);

// gets the end time and duration
$time_end = microtime(true);

// write time to hdd, database, whatever
// ...
error_log("Processing time: ". sprintf("%.4f", ($time_end-$time_start))." seconds");
?>

Please do remember that the $filename = $_GET['filename'] is example only and should be properly escaped so that people can't hack into your server.

EDIT:
Altered to check if it really worked - Mark made me question it! ;) Needed minor tweaking (especially on microtime) but yes, it does work!