file downloads accounting

tanis

I'm trying to build something very similar to what fileplanet.com already does.

I'm going to let users download files through a php script that constantly monitors how many transfers are going on and keeps the user on a queue until a new slot has opened.

Now I'm stuck trying to manage the queue, since I know when a user starts a download, but I can't find a way to tell if he's finished transferring the file or if he's aborted it.
I tried doing it that way (in my php script):

count how many rows are in the queue table
if they're below 50 let's write a new entry in the table with this user's data.
start the download by outputting the various headers with Content-Disposition and all the rest
send the file through readfile()
I thought that after readfile has finished I can safely say that the user has finished transferring or has aborted (though I still don't know how to say which is the case). But everything I put after readfile() does not get executed.

Any ideas?

Wave

perhaps this will be right way for you

http://us.php.net/manual/en/function.register-shutdown-function.php

tanis

I tried using this function, but it works only when you're sure that the user is going to behave well. by this I mean that he should close all of his browser's windows that are keeping the session alive. It's not just the current page that does the trick.

I tried this way now:

I have a main page with a button that opens a popup window.
In the popup you choose to stay in the queue by clicking on a "Yes" button and then a page is called that keeps checking if it's your turn. When your turn comes you're prompted to download.
if you download the file till the end, you're done and it works a charm.
But ig you cancel the download or simply close the window, I cannot tell that you're no longer in the queue. How could I check this case??

Zaerion

i would also like to learn how to see if a download is finished and how to see if a download was aborted. i'm trying to make a download queue system like fileplanet or soundblaster.com

thanks

tanis

I think I've solved the problem, but at the moment I cannot say much more since the code has been developed for one of my contractors. I shall see if I can publish some extracts of it in the future.

Zaerion

i can understand that. i've been trying to figure out how to tell if the user cancelled a download. at this point all i really need to to only allow them to download one file at a time. i've gotten it to work, but only if they don't cancel the download. if they cancel the download, they won't be able to start another one without closing the browser windows to end the session. anything you can help me with would be appreciated.. a point in the right direction perhaps.

thanks,
zaerion

tanis

I'm tracking users behaviour by using a table to store their download progress status.

It's something like:

user_id
file_id
lastupdate

'lastupdate' is a column that holds a timestamp of the last time that row was updated. If the difference between the current time and 'lastupdate' is more than 120 secs I delete the row so that the user can try again to download the file. You can obviously tune it for the exact time. You can bring it down to 10 secs but then you have to be sure that the user transfers at least some packets every 10 seconds.

Do not do the update on the table for every transferred packet or you would bring up issues with db performances. You'd rather update it at fixed time intervals while downloading.

I hope I've been clear enough and have given you some pointers.