My, you always have an answer to everything...
Well, I've had to work with it in the past, hence I did know about it. Plus there are plenty of places where it actually checks settings_updated to avoid calling on cache (usually where on level 2+ where the cache key is the only thing, there won't be a way of invalidating it so easily)
So, in order to retrieve the cache hash, I would need to first get the cache hash and then retrieve the cache based on that cache hash... THEN I can know what the cache hash is :^^;:
It is sort of complicated, yes
:PHmm, I was thinking... md5() is a 128-bit number, so it's something like at least a billion billion billion billion... Thinking about it, since we can barely have more than 2000 files in a folder, it's very, very unlikely to get a collision -- ever... No?
It's not quite like that, no. The problem with cache keys is that they're all in the one folder - everything goes into $cachedir, and everything would notionally get the same md5() process applied, so you're not just considering collisions across the namespace of a single album's files, but collisions across everything that the md5() is applied to, which is potentially every media item (since we only need apply the md5 if there isn't a / in the supplied cache key)
That said, md5 might be 128 bits, but it's not 128-bit wide in collision cases. It was proved a few years ago that for collision purposes, the keyspace isn't 2^128 but more like 2^40 due to weaknesses in the way it's generated.
I forgot about the slash being a valid base64 char. Oh, my... They should have chosen something else! It's not like there are so few valid characters for an URI...
Actually, there aren't that many characters truly valid in a URI, the vast majority of them have... extra meanings, and are normally just %-encoded instead.
Hmm, I like that... bin2hex seems to be fast indeed.
I was also looking into sha1(), crypt('sha256') and pack() (there are plenty of options to convert these), or even using base_convert() to automatically use alphanumeric characters only...
But bin2hex could be just as simple :P
Although not as secure as a md5() on boardurl.filemtime...
Certainly it's fast, and for short keys it's faster than even base64. I'd avoid crypt, though, there were issues with it and related functions in 5.3.7, pack() is really just a super-sized version of what bin2hex is doing anyway, heh.
You're right, it's not as secure as md5ing the filemtime, and that's reasonably important for the sake of safety.
Oh, Pete -- how about we calculate that md5 hash only ONCE per page...? It seems stupid not to do it. We could simply store it in $context['cache_hash'] or something... If empty, just fill it in...
Works for me.
:) 
This topic was marked solved by its starter, on December 14th, 2012, 01:23 AM
