Re: Patch for simple walk caching

On Dec 7, 2004, at 7:56 AM, Bill Mill wrote:

> What if there was a function invalidate_cache(path) - and when a
> plugin received an update to a page, it would invalidate the cache for
> that path. From the client (plugin) side, ideally it would look
> something like:
>
> if config['cache_dir']:                        #if using cache
>     invalidate(path_to_changed_file)   #invalidate the path

I think this is the kind of client API I was looking for

>
> the problem is from the cache server side - how does it figure out
> which caches include that file? Does it open and search through all of
> them? Can you launch a background thread from a CGI script? If you
> can, then the user shouldn't experience too much delay, and his
> changes should be implemented soon but not instantly. If not, he's
> going to have to wait a while before his change is implemented.

Once you have a cache, then you have to manage it, which is why I didn't
try to get all fancy.  It's especially tough in pyblosxom because there
are so many legal paths.

>
> The other thought I have would be to maintain a listing of what files
> are in what caches. However, it's obviously really crucial to keep
> overhead on the cache as low as possible, or the fix becomes the
> problem.
>
> Also, as Wari said, permalinks don't even benefit from caching much.
> The question is how to determine that something is a permalink - I
> think I'll just set the cache up to ignore filelists with only one
> entry.

I'm not all the concerned about permalinks, although I suppose I
might be if my readership grew a lot (unlikely).  If my front page and
RSS feed (which I haven't timed at all) go faster, then I'll be happy.

>
> Thanks for trying the patch out and for the ideas on how to improve
> it; I think optimization is all kinds of fun, so I'll play with it
> some today.

----
Ted Leung                          Blog: <http://www.sauria.com/blog>
PGP Fingerprint: 1003 7870 251F FA71 A59A  CEE3 BEBA 2B87 F5FC 4B42



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