Re: ENTRY_SPECIAL => content pinning?

It also looks like ENTRY_SPECIAL ignores some things that I don't know
that we want PINNED objects to ignore...Specifically:

     if (EBIT_TEST(e->flags, ENTRY_SPECIAL)) {
         /* Special entries are always hits, no matter what the client
says */
         debug(33, 3) ("clientProcessRequest2: ENTRY_SPECIAL HIT\n");
         http->entry = e;
         return LOG_TCP_HIT;

I don't think we want pinned objects to always HIT. If so, it would
need to be a configurable option...I think the goal of a pinned object
is that it always has room to be cached, and takes priority over
non-pinned entries. But we don't want pinning to override freshness and
other such things. Do we?

Just some thoughts...

Joe Cooper wrote:
> Hi Yee Man,
>
> I was looking at this myself. I think you've missed the store_swapout.c
> reference to ENTRY_SPECIAL...if you made this the entry type for pinned
> objects they would never get to disk.
>
> I think adding a new type "ENTRY_PINNED" that behaves sort of like
> ENTRY_SPECIAL, without the swapout limitation might be more intuitive
> and self-explanatory for folks reading the code.
>
> My thoughts have run to implementation details: Should pinning use ACLs
> or a pattern like 'refresh_pattern'?
>
> Yee Man Chan wrote:
>
>> Hi
>>
>> I read some posts in isp-caching and people are
>> talking about content pinning, ie store something in
>> cache and it will never be purged. I see that in our
>> removal policy modules, we ignore all ENTRY_SPECIAL
>> entries. Is it true that if we set the objects we want
>> to pin to ENTRY_SPECIAL, then we can achieve content
>> pinning?
>>
>> Thanks.
>> Yee Man
>>
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>
>
>
>

-- 
Joe Cooper <joe@swelltech.com>
Web caching appliances and support.
http://www.swelltech.com