CacheDir(3) User Contributed Perl Documentation CacheDir(3)
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File::CacheDir - Perl module to aid in keeping track and
cleaning up files, quickly and without a cron $Id:
CacheDir.pm,v 1.15 2001/10/16 17:07:57 earl Exp $
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CacheDir takes up to three parameters and returns a fully
qualified filename. Cool part is that it quickly and
automatically cleans up files that are too old.
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The possible named arguments (which can be named or sent
in a hash ref, see below for an example) are,
filename - which is what you want the file
without the directory to be named,
like "storebuilder" . time . $$
I would suggest using a script
specific word (like the name of the cgi),
time and $$ (which is the pid number)
in the filename, just so files
are easy to track and the filenames
are pretty unique
default is time . $$
ttl - how long you want the file to stick around
can be given in seconds (3600) or like
"1 hour" or "1 day" or even "1 week"
default is '1 day'
base_dir - the base directory
default is '/tmp/cache_dir'
content_typed - whether or not you have printed a
Content-type header
default is 0
set_cookie - whether or not to set a cookie
default is 0
cookie_name - the name of your cookie
default is 'cache_dir'
cookie_path - the path for your cookie
default is '/'
carry_forward - whether or not to move forward the file
when time periods get crossed for example
if your ttl is 3600, and you move from the
278711 to the 278712 hour, if carry
forward is set, it will refresh a cookie
(if set_cookie is true) and move the file
to the new location
default is 1
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Since CacheDir fits in so nicely with cookies, I use a few
CGI methods to automatically set cookies, retrieve the
cookies, and use the cookies when applicable. The cookie
methods make it near trivial to handle session
information. Taking the advice of Rob Brown
<
[email protected]>, I use CGI.pm, though it increases
load time and nearly doubles out of the box memory
required.
The cookie that gets set is the full path of the file with
your base_dir swapped out. This makes it nice for users
to not know full path to your files. The filename that
gets returned from a cache_dir call, however is the full
path.
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Most of the time, the defaults will suffice, but by having
code refs in your object, you can override most everything
CacheDir does. To how the code refs are used, I walk
through the code with a simple example.
my $cache_dir = File::CacheDir->new({
base_dir => '/tmp/example',
ttl => '2 hours',
filename => 'example.' . time . ".$$", });
An object gets created, with the hash passed getting
blessed in.
my $filename = $cache_dir->cache_dir;
The ttl gets converted to seconds, here 7200. The
$ttl_dir = $base_dir . $ttl;
In our example, $ttl_dir = "/tmp/example/7200";
$self->{ttl_mkpath} - if the ttl directory does not exist,
it gets made with this code ref
Next, the number of ttl units since epoch, here it is
something like 137738. This is
$self->{int_time} = int(time/$self->{ttl});
Now, the full directory can be formed
$self->{full_dir} = $ttl_dir . $self->{int_time};
If $self->{full_dir} exists, $self->{full_dir} .
$self->{filename} gets returned. Otherwise, I look
through the $ttl_dir, and for each directory that is too
old (more than two units away) I run
$self->{cleanup} - just deletes the old directory, but
this is where a backup could take place, or whatever you
like.
Finally, I
$self->{sub_mkdir} - makes the new directory,
$self->{full_dir}
and return the $filename
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#!/usr/bin/perl -w
use strict;
use File::CacheDir qw(cache_dir);
my $filename = cache_dir({
base_dir => '/tmp',
ttl => '2 hours',
filename => 'example.' . time . ".$$",
});
`touch $filename`;
2001-10-17 perl v5.6.0 1
