Re: [PATCH] Support client connection annotation by helpers via clt_conn_id=ID

On 15/06/2014 4:58 a.m., Alex Rousskov wrote:
> On 06/11/2014 08:52 AM, Tsantilas Christos wrote:
>
>> I must also note that this patch adds an inconsistency. All annotation
>> key=values pairs received from helpers, accumulated to the existing key
>> notes values. The clt_conn_id=Id pair is always unique and replaces the
>> existing clt_conn_id=Id annotation pair.
>> We may want to make all annotations unique, or maybe implement a
>> configuration mechanism to define which annotations are overwriting
>> their previous values and which appending the new values.
>
> I suggest making all annotations unique (i.e., new values overwrite old
> ones) because helpers that want to accumulate annotation values can do
> that by returning old values along with new ones:
>
> received by helper: name=v1
> returned by helper: name=v1,v2
>
> Please note that the opposite does not work: If annotation values are
> always accumulated, a helper cannot overwrite/remove the old value.
>

Doing that would mean passing all existing annotations to every helper
lookup. Which would seriously degrade the helper result caching.

Amos
Received on Sun Jun 15 2014 - 06:07:50 MDT