Cache::Reddit or: how to use social media as a temporary data store

Sometimes crazy ideas are brilliant, but most of the time they are just crazy. I recently uploaded a new module to CPAN: Cache::Reddit. It’s a caching module with a twist: it saves cached data as text posts on Reddit. Is that a good idea? Probably not, it’s definitely crazy.


You probably don’t want to do this, but if you were considering using the module, here’s how. First you’ll need a Reddit account with enough karma to use the API (usually handful of upvoted links and comments is enough). Second you should create your own subreddit to post to. Install Cache::Reddit using the command line clients cpan or cpanm

$ cpan Cache::Reddit


$ cpanm Cache::Reddit

Finally set the environment variables: reddit_username, reddit_password, and reddit_subreddit (the name of the subreddit that data will be posted to). On Linux / OSX you can do this at the terminal:

$ export reddit_username=somename
$ export reddit_password=itsasecret
$ export reddit_subreddit=mycache

To set environment variables on Windows 8, these steps might work.

Using Cache::Reddit

The module exports the typical caching functions you’d expect: set for saving data, get for retrieval and remove for removal. For example:

use Cache::Reddit; #exports get, set, remove

my $monthly_revenues = { jan => 25000, feb => 23500, mar => 31000, apr => 15000 };
my $key = set($monthly_revenues); # serialize and save on reddit
my $revenue_data = get($key);


Although the data is stored in a failsafe, redundant, backed-up environment in the cloud, frequent users of Reddit will appreciate that the service is likely to unavailable for a few seconds multiple times a day.

Retrieval from the cache using get doesn’t use a hash lookup; instead Cache::Reddit iterates through all available posts on the subreddit until it finds a match. This yields 0(n) performance, which means that the get function will get slower the more items are cached. This is not likely to be a performance bottleneck though, as typically a subreddit only holds 1,000 links before they are lost to the ether.

The data is serialized and deserialized using Storable, which may open pose a security risk if the cached data is edited by a mod. Up to 40,000 characters of data can be stored at one time. Unless the subreddit permits both links and text posts, in which case the limit is 10,000 characters. But Cache::Reddit does boast 100% test coverage.

Looking forwards

In the future I’d like to take advantage of Reddit’s voting system to implement a crude LRU cache. Comments could prove to be a powerful version control system. Patches welcome, the source code is on Instagram.


David Farrell

David is the founder and editor of An organizer of the New York Perl Meetup, he works as a technology consultant in New York City.

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