[Varnish] #412: make caching still possible in case of 'restart' from vcl_fetch and implement 'restart' from vcl_hit

[Varnish]

#412: make caching still possible in case of 'restart' from vcl_fetch and
implement 'restart' from vcl_hit
-------------------------+--------------------------------------------------
 Reporter:  hajile       |       Owner:  phk  
     Type:  enhancement  |      Status:  new  
 Priority:  normal       |   Milestone:       
Component:  varnishd     |     Version:  trunk
 Severity:  normal       |    Keywords:       
-------------------------+--------------------------------------------------
 This is useful for caching redirects and following them internally (to
 minimize network traffic)

 for example with this config (internally following 303: See Other):

 {{{
 backend test {
  .host = "127.0.0.1";
  .port = "8080";
 }

 sub vcl_hit {
  if (obj.http.X-Magic-Redirect == "1") {
   set req.url = obj.http.Location;
   restart;
  }
 }

 sub vcl_fetch {
  if (obj.status == 303) {
   set obj.cacheable = true;
   set obj.http.X-Magic-Redirect = "1";
   set req.url = obj.http.Location;
   restart;
  }
 }

 }}}


 {{{
 --- varnish-2.0.2-orig/bin/varnishd/cache_center.c      2008-12-17
 19:26:58.000000000 +0300
 +++ varnish-2.0.2/bin/varnishd/cache_center.c   2008-12-17
 19:36:43.000000000 +0300
 @@ -413,8 +413,13 @@

         switch (sp->handling) {
         case VCL_RET_RESTART:
 -               sp->obj->ttl = 0;
 -               sp->obj->cacheable = 0;
 +               if (sp->obj->ttl == 0) {
 +                       sp->obj->cacheable = 0;
 +               }
 +               if (sp->obj->objhead != NULL && sp->obj->cacheable == 1) {
 +                       VRY_Create(sp);
 +                       EXP_Insert(sp->obj);
 +               }
                 HSH_Unbusy(sp);
                 HSH_Deref(sp->obj);
                 sp->obj = NULL;
 @@ -529,6 +534,14 @@

         VCL_hit_method(sp);

 +       if (sp->handling == VCL_RET_RESTART) {
 +               sp->step = STP_RECV;
 +               HSH_Deref(sp->obj);
 +               sp->obj = NULL;
 +               sp->director = NULL;
 +               return (0);
 +       }
 +
         if (sp->handling == VCL_RET_DELIVER) {
                 /* Dispose of any body part of the request */
                 FetchReqBody(sp);
 }}}

-- 
Ticket URL: <http://varnish.projects.linpro.no/ticket/412>
Varnish <http://varnish.projects.linpro.no/>
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