[RFC][Icedtea-web]: Changed how cache works.

[Andrew Su]

----- Original Message -----
> Hi again.
> 
> My previous e-mail was mostly just low level implementation
> comments. I have only one problem with the design:
> right now our cache management metadata is stored in RecentlyUsed
> which is a <leastRecentModification, fileName> map. Storing
> information about the time of last update of a cached
> resource using the time as a key seems very unnatural to me.
> 
> Right now, CacheLRUPolicy.cacheOrder isn't really a hash map
> at all. It's just a list of <time, name> couples because
> every time we read from it we start out with the name and try
> to read the time. In other words, given the value we try to
> read the key. That is very backwards for a hash map, which
> is supposed to provide the value given the key.
> 
> If we could somehow make the resource that we're caching the
> key and the time of last update the value, I think that would
> simplify things a lot. In particular we might be able to
> entirely get rid of these identifiers that we're adding to
> folder names and times. And also checking whether something
> is in the cache and updating it should be made much simpler
> (no loops would be required).
> 
> What do you think?
Hi Denis,

At first it sounded like a good idea to me. However, after closer inspection it comes with the issue that when let's say you try check for something on www.example.com/example.jar, using that we can use it to check that it's a key, but when it comes time to update (download a new copy) it'd need to store it in a separate location (which in the end we will be looping over the keys). Overwriting any of the jar files is bad since we don't know if they are in use.

I hope that made sense..

--snip--

Cheers,
  Andrew