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    Is it possible in any way to force the check before the result is
    send to the client?<br>
    <br>
    Jan Hugo<br>
    <br>
    <br>
    <div class="moz-cite-prefix">On 01/24/2017 10:17 AM, Guillaume
      Quintard wrote:<br>
    </div>
    <blockquote
cite="mid:CAJ6ZYQxXWS45RGARvu8LwXwAM7J0zxsy44=bEbq=sXc730+qjQ@mail.gmail.com"
      type="cite">
      <div dir="auto">Hello,
        <div dir="auto"><br>
        </div>
        <div dir="auto">Indeed, with this vcl code, the object is
          checked asynchronously. So, if the check fails, the user that
          triggered the check will have received the outdated object. It
          may or may not be an issue depending on your use case.</div>
        <div dir="auto"><br>
        </div>
        <div dir="auto">Note that you can reduce the TTL further.</div>
      </div>
      <div class="gmail_extra"><br>
        <div class="gmail_quote">On Jan 24, 2017 03:11, "Jan Hugo Prins
          | BetterBe" <<a moz-do-not-send="true"
            href="mailto:jprins@betterbe.com">jprins@betterbe.com</a>>
          wrote:<br type="attribution">
          <blockquote class="gmail_quote" style="margin:0 0 0
            .8ex;border-left:1px #ccc solid;padding-left:1ex">
            <div bgcolor="#FFFFFF" text="#000000"> After reading this
              mail and doing a lot more searching in the mailinglist and
              on the web, I think it is actually rather simple. At least
              I think that I'm seeing the correct behaviour. I'm not
              sure though, it could be that the response is first
              generated and that the origin is only checked after the
              response has been send to the client. What I have now in
              my vcl_backend_response is nothing more then:<br>
              <br>
              sub vcl_backend_response {<br>
                  if (beresp.http.Cache-Control ~ "must-revalidate") {<br>
                      set beresp.ttl = 1s;<br>
                      set beresp.keep = 3600s;<br>
                      set beresp.grace = 3600s;<br>
                  }<br>
                  return (deliver);<br>
              }<br>
              <br>
              <br>
              Jan Hugo Prins<br>
              <br>
              <br>
              <br>
              <div class="m_2639926546421627218moz-cite-prefix">On
                01/23/2017 02:20 PM, Geoff Simmons wrote:<br>
              </div>
              <blockquote type="cite">
                <pre>On 01/23/2017 01:56 PM, Jan Hugo Prins | BetterBe wrote:
</pre>
                <blockquote type="cite">
                  <pre>Somewhere I found an old Trac Wiki document that describes
something like this, but I can't figure out if this has been
implemented or not. 
<a moz-do-not-send="true" class="m_2639926546421627218moz-txt-link-freetext" href="https://www.varnish-cache.org/trac/wiki/BackendConditionalRequests?version=8" target="_blank">https://www.varnish-cache.org/<wbr>trac/wiki/<wbr>BackendConditionalRequests?<wbr>version=8</a>
</pre>
      </blockquote>
      <pre>That
</pre>
      <blockquote type="cite">
        
      </blockquote>
      <pre>Wiki page is obsolete -- it was about an experimental branch that
was developed while Varnish 3 was the released version.

(Maybe we should delete the Wiki page, it's not the first time someone
has been led astray.)

Varnish has supported 304 responses to client requests with
If-Modified-Since/If-None-<wbr>Match for as long as I've known about it
(going back to Varnish 2). Backend conditional requests have been
supported since Varnish 4.

However, by default that doesn't quite work as your flow chart
indicates, if I've understood it correctly. If the client request is
for a cached response with an unelapsed TTL, then Varnish delivers the
cached response unconditionally, without re-validating the response
with the backend. Conditional requests to backends are done for the
fetch after the TTL elapses.

That's the default, but I believe you can get your own VCL to
implement re-validation after cache hits. I haven't tried that myself
-- maybe someone reading the list has some working VCL they can share?


Best,
Geoff
</pre>
    </blockquote>
    

    <div class="m_2639926546421627218moz-signature">-- 

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        vriendelijke groet / Best regards,

        

        Jan Hugo Prins

        <i>Infra and Storage consultant</i>
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</blockquote>
<div class="moz-signature">-- 
<p style="font-family: Arial,Roboto;font-size: 13px;color: #000000;line-height: 20px;margin:0px;margin-top:20px;margin-bottom:50px;">
    Met vriendelijke groet / Best regards,

    

    Jan Hugo Prins

    <i>Infra and Storage consultant</i>
</p>

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