Any way to invoke code from VCL after a request has been serviced?

[Ryan Burn]

Thanks Reza and Guillaume. I didn't realize there was a way to set up
callbacks on the VSM. I think either of the approaches will work for
me.

On Mon, May 8, 2017 at 12:13 PM, Guillaume Quintard
<guillaume at varnish-software.com> wrote:
>
> That's the way to do it in a vmod, indeed.
>
> However Ryan, I don't get why you are reluctant to use the logs. By using
> the c api, you can just define callbacks and get called everything a
> request/transaction ends, so you don't need to read regularly.
> --
> Guillaume Quintard
>
>
> On May 8, 2017 17:45, "Reza Naghibi" <reza at varnish-software.com> wrote:
>
> You can do this in a VMOD via PRIV_TASK:
>
>
> --
> Reza Naghibi
> Varnish Software
>
> On Fri, May 5, 2017 at 10:15 PM, Ryan Burn <rnickb731 at gmail.com> wrote:
>>
>> Hello,
>> From VCL, is it possible to execute code that runs after a request has
>> been processed?
>>
>> I'm looking into writing a module that enables Varnish for distributed
>> tracing using the OpenTracing project [opentracing.io]. This requires
>> invoking code at the beginning of a request to start a span and insert
>> tracing context into the request's headers and invoking code after a
>> request's been processed to finish the span and measure how long it
>> took to process.
>>
>> I recently did a similar project for nginx
>> [github.com/rnburn/nginx-opentracing]. Nginx provides an
>> NGX_HTTP_LOG_PHASE [www.nginxguts.com/2011/01/phases/] that allows you
>> to set up handlers run after requests are serviced. Can anything
>> equivalent be done using VCL?
>>
>> I image you could accomplish this by subscribing and regularly reading
>> from Varnish's shared memory log, but I'd much rather do it directly
>> if possible.
>>
>> Thanks, Ryan
>>
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>
>
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