[squid-dev] Proposal: Helper response: concatenated values with custom delimiter

[Amos Jeffries]

On 24/04/2026 01:42, Alex Rousskov wrote:
> On 2026-04-22 07:24, Andrey K wrote:
>> Hello, Amos and Alex,
>>
>> Thank you for the discussion and the proposed formats.
>>
>> Since we already support the
>>      key=v1 key=v2
>> format, and the
>>      key=v1,v2
>> format is currently undocumented, I think we should answer two 
>> questions first:
>>
>> 1. Do we really need to support list-values? It seems Alex thinks we 
>> might not need them at all.
> 
> If you have to ask, then the answer is "no" or "not yet": We need a very 
> compelling use case to add a "list-values" optimization (when we already 
> support lists of values). Since you are not sure, and you were the only 
> one making/wanting related changes (AFAICT), we evidently lack such a 
> case today.
> 
> Rule of thumb: Avoid complex optimizations until their expense can be 
> justified by a use case (that can also guide their implementation).
> 

Remember that the earlier work by Andrey did bring up a reasonable 
rational for doing it anyway.

Namely that supporting A,B,C lists improves the bandwidth cost of 
transmission between helper and Squid.

Several of the Kerberos use-cases are sending many group names out of 
the helper.  So this specific (accept comma-delimited value list) is not 
a theoretical optimization.


Cheers
Amos