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From Alan Carroll <solidwallofc...@oath.com>
Subject Re: Avoiding TCP_REFRESH_HIT
Date Thu, 23 Nov 2017 16:38:54 GMT
You might try fiddling with the 'cache.config' file and set a cache TTL of
10 years or so.

On Thu, Nov 23, 2017 at 10:11 AM, Veiko Kukk <veiko.kukk@gmail.com> wrote:

> Hi David,
>
> Objects are not fetched from ATS via browser. ATS is just internal cache.
> Only problem is to trick ATS into believing that object is always fresh,
> never stale.
> I wonder if modifying headers before ATS (READ_RESPONSE_HDR_HOOK) removing
> or changing Expires and/or adding max-age to some very big value might be
> right way to go for me.
>
> Veiko
>
>
> 2017-11-23 17:52 GMT+02:00 David Carlin <dcarlin@oath.com>:
>
>> Have you considered adding "Cache-Control: Immutable" to these objects
>> which will never require re-validation?  This will prevent the browser from
>> attempting an If-Modified-Since request.
>>
>> https://hacks.mozilla.org/2017/01/using-immutable-caching-
>> to-speed-up-the-web/
>>
>> David
>>
>> On Thu, Nov 23, 2017 at 10:07 AM, Veiko Kukk <veiko.kukk@gmail.com>
>> wrote:
>>
>>> In addition to my previous e-mail, headers that are provided by source
>>> to ATS:
>>>
>>> < HTTP/1.1 200 OK
>>> < Content-Length: 1185954
>>> < Accept-Ranges: bytes
>>> < Last-Modified: Mon, 02 Nov 2015 17:56:12 GMT
>>> < Etag: 92ef40097ba87bdf09efcf7e1cefd32a
>>> < X-Timestamp: 1446486971.39466
>>> < Content-Type: application/octet-stream
>>> < Content-Disposition: attachment; filename="ABIYohNyPrJNjvFsAdgN5wc8D-8Yo4ZO.m4s";
>>> filename*=UTF-8''ABIYohNyPrJNjvFsAdgN5wc8D-8Yo4ZO.m4s
>>> < Expires: Thu, 23 Nov 2017 15:27:30 GMT
>>> < X-Trans-Id: tx3a0af5473d5c41d38195c-005a16e30d
>>> < X-Openstack-Request-Id: tx3a0af5473d5c41d38195c-005a16e30d
>>> < Date: Thu, 23 Nov 2017 15:02:37 GMT
>>> < X-IPLB-Instance: 12631
>>>
>>> I assume, Expires header is here to blame and must be overriden in ATS
>>> config, but how? I don't have control over source, its Openstack Swift
>>> object storage.
>>>
>>> Veiko
>>>
>>>
>>> 2017-11-23 16:35 GMT+02:00 Veiko Kukk <veiko.kukk@gmail.com>:
>>>
>>>> Hi,
>>>>
>>>> Could ATS in reverse proxy mode be configured such way that it would
>>>> never try to revalidate from source? It is known that in our case, object
>>>> never changes (and is never refetched from source) and it is desirable to
>>>> avoid any source validation. Validation verification adds significant
>>>> overhead and we need to avoid it. Response to client with TCP_REFRESH_HIT
>>>> would take 100-200ms instead of 0-10 in case of direct local TCP_HIT.
>>>>
>>>> I've configured following:
>>>> dest_domain=.*.source.tld action=ignore-no-cache
>>>> dest_domain=.*.source.tld revalidate=9999d
>>>> dest_domain=.*.source.tld ttl-in-cache=9999d
>>>>
>>>> CONFIG proxy.config.http.cache.when_to_revalidate INT 3
>>>> CONFIG proxy.config.http.cache.required_headers INT 0
>>>>
>>>> But i still get TCP_REFRESH_HIT even when 9999 days have not passed
>>>> (obviously).
>>>>
>>>> NB! ATS is used as internal cache and our 'client' never explicitly
>>>> requests revalidation.
>>>>
>>>> Thanks,
>>>> Veiko
>>>>
>>>>
>>>
>>
>

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