Why bother with re-writing a file every time? Look at, say, BerkeleyDB, which maintains an efficient key/value pair database.

What you're talking about is being able to re-order existing records. The best strategy for this might be to use a single BerkeleyDB database, and re-define the keys from time to time to re-define the order of the posts. So in the value of each record, you maintain the time of the post (so you can get latest-first), and the ID or quality ranking of the poster, as well as the messsage. You generate your keys to the most significant few (say, 4) bytes supply a serial number that gives the number of re-order passes. This way, as you re-order records, they go to the end of the database, and you can then delete them from the beginning.

Each time you re-order, you do this:

increment the re-order sequence number
For each record that was not re-ordered this time through,
   read the record
   re-compute the key based on the age and poster ID
   write the new key/value pair (with the new re-order number)
   delete the old key/value pair

[download]

The beauty of this is that BerkeleyDB will efficiently reclaim the file space with a minimum of work. When you have new messages, you just give them a key that will allow you to find them before the previous messages (cursors in BerkeleyDB can go forwards (DB_NEXT) or backwards (DB_PREV)).

In reply to Re: Message Board Mangling by bikeNomad
in thread Message Board Mangling by achiles

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