tedd wrote:
Hi gang:
Here's the logic problem.
First the site:
http://php1.net/b/zip-files/
Now, the site works well enough. The user selects what they want, clicks
Submit, the order is assembled in zip file and presented to the user for
downloading.
However, as it stands now, before the script assembles the test.zip, it
deletes (unlinks) the previous test.zip and therein lies the problem.
If two, or more, users hit the site at the same time then a RACE
condition may have one user getting something they didn't ask for or not
getting anything at all.
The complicated way I figure I could solve this would be to:
1. Generate a random string name for the file -- instead of test.zip, it
could be ax12nhg34.zip.
2. Then when the user selects the download that would trigger a
javascript routine that would send the name of the file to be deleted to
a slave php script that would unlinks the file.
I know this will work, but if the user never downloads the file, then
the files accumulate on the server.
Does anyone have a better idea?
Thanks,
tedd
Everybody so far has had excellent descriptions of what to do. I would
do almost everything they recommend. Except, if I had the hard drive
space to make all the possible permutation and allow them to down load
the file that someone else had created, I would do that. Rather then
possibly rebuilding an identical file over and over again.
So, I guess I need to ask this question. Are their to many files in
your download selection too make the number of possible zip archives out
of the question to be cached? If that is the case, then I would delete
old ones using a cron/task schedule type program. But I would do it
much quicker, say every three to seven days.
if you are limited on space, you will need to protect yourself against
bots that might try, accidentally of course, to to make you run out of
HD space. At this point, you might have to build something into your
php script to manage the file space consumption.
Jim
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