On 27/01/11 23:25, IGnatius T Foobar wrote:
Ok. This solves the problem of "I can request arbitrary msgnums and the server
will give them to me whether or not they exist in a room to which I have access"
-- which was only a minor nuisance before, but with Citadel sites being exposed
to the public Internet with anonymous guest mode enabled, that would have
become quite a large problem. Imagine how lovely it would be if Google indexed
it all. :)
Unfortunately it takes a little more memory than I wanted it to.
I'm also concerned about the binary tree:
If the binary tree is not bulk-populated at the start and in a balanced
fashion, but rather as messages are seen, then if messages are seen in
mostly numerical order, which will happen in folders with large numbers
of messages - the sorts of folders where we really want the benefit of a
binary tree, then we will end up with an unbalanced binary tree, which
will be as bad as a linear search but taking up a lot more memory.
Further, if the tree caches "seen" message, it means that if a message
has been seen at all in a session, it can always be seen until the
session logs out, even if the message has been removed from all rooms
available to the user. In other words it makes it hard to withdraw
access. Maybe the user hadn't even read the message, but merely had it
loaded into a room index. The admin moves the message to a restricted
room, but all users who ever had it listed in their index can still see
it until they log out.
It seems to me that the new code is worse than the old code in terms of
memory usage, not better in terms of the cases that ought to benefit,
and worse in terms of security.
I think the binary search of the linear list that was committed is a
better solution. If a binary tree is used, it should be a balanced tree.
I think there are bigger potential performance gains than can be had
here, if performance is a problem.
Sam
