On 5/3/06, Graham Leggett <[EMAIL PROTECTED]> wrote:
Gonzalo Arana wrote:
> again, I am in the dark: why do cache request headers may need to be
> replaced or edited in the same entity?
It's a requirement of the HTTP/1.1 spec.
<snip>
non-modified response headers to conditional requests need to update
cached response headers.
</snip>
<snip>
we should try to avoid 'dialog' with cache backend.
</snip>
The catch is when the server sent "304 Not Modified" - you need to
update your cache to say "yep, my cached entry is still fresh", ie
update the headers, without touching the body, which hasn't changed.
I see the light now :).
Having a single cache_admin proc/thread would make this easier, since
any operation can be presented as atomic, while it may require more
than a single syscall (I know, the goal is avoid full entity
duplication). Anyway, I guess a good policy is to have 'editable'
content as binary data (i.e., no variable length). Perhaps this is
not possible anyway :(.
Of course, to avoid a 'dialog' between httpd process and cache_admin,
both cache_admin and httpd must be smart enough.
> That's why I suggested a dedicated process/thread for cache
> administration, which is not a good idea if too many lookups are
> issued to this process on each request received.
<snip>
I think in the long run, a dedicated process is the way to go.
+1 :).
Regards,
--
Gonzalo A. Arana
