[varnish] Re: [varnish] Re: Handling of cache-control

[Bedis 9]

hey,

That way, any shared proxy cache on the path between our caches and
the client would cache the object.
Our customer didn't want this. The purpose was to have the freshest
information as close as the origin as possible.

cheers


On Thu, Jan 28, 2010 at 12:00 AM, pablort <pablort+varnish at gmail.com> wrote:
> Isn't this the equivalent of and max-age=5 and s-maxage=0 ?
>
> On Wed, Jan 20, 2010 at 7:19 AM, Bedis 9 <bedis9 at gmail.com> wrote:
>>
>> Hi,
>>
>> Netcache devices had the X-Accel-Cache-Control headers in order to
>> allow an origin server to setup different Cache-Control parameters for
>> the cache and the end-user.
>> The netcache will follow the X-Accel-Cache-Control while the end user
>> will follow the Cache-Control.
>>
>> I've a few customer using this, mainly for sports events where "live"
>> is the key.
>> They setup X-Accel-Cache-Control to max-age=5 while Cache-Control is
>> set to no-cache.
>> That way, all the load generated by thousends of request per second
>> for "live" stuff is offloaded to the cache layer.
>> Only a few request goes back to the origin.
>>
>>
>> I was able to reproduce such behavior with the following inline C:
>> sub vcl_fetch {
>> [...]
>> # Check if X-Accel-Cache-Control exists and follow it
>>        if (obj.http.X-Accel-Cache-Control) {
>> C{
>>        char *cache;
>>        int max_age = 0;
>>        cache = VRT_GetHdr(sp, HDR_OBJ, "\026X-Accel-Cache-Control:");
>>        if(cache) {
>>                char *s = NULL;
>>                /* Looking for max-age */
>>                if (s = strstr(cache, "max-age=")) {
>>                        s+=8;
>>                        max_age = strtoul(s, 0, 0);
>>                        if (max_age) {
>>                                VRT_l_obj_ttl(sp, max_age);
>>                        }
>>                }
>>        }
>> }C
>>       unset obj.http.X-Accel-Cache-Control;
>>        }
>>
>> # Cache-Control and Pragma headers preventing caching
>>        if ((!obj.http.X-Accel-Cache-Control) && (obj.http.Pragma ~
>> "no-cache" || obj.http.Cache-Control ~ "(no-cache|no-store|private)"))
>> {
>>                pass;
>>        }
>>
>> }
>>
>> [...]
>>
>> }
>>
>>
>> Maybe it can be useful to somebody else :)
>>
>> cheers
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>> varnish-misc at projects.linpro.no
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>
>