Method issue_revalidate

src/proxy/http/HttpTransact.cc:2442–2561

////////////////////////////////////////////////////////////////////////// Name : issue_revalidate Description: Sets cache action and does various bookkeeping Details : The Cache Lookup was hit but the document was stale so after calling build_request, we need setup up the cache action, set the via code, and possibly conditionalize the request The paths that we take to get this code a

//
///////////////////////////////////////////////////////////////////////////////
void
HttpTransact::issue_revalidate(State *s)
{
  HTTPHdr *c_resp = find_appropriate_cached_resp(s);
  SET_VIA_STRING(VIA_CACHE_RESULT, VIA_IN_CACHE_STALE);
  ink_assert(GET_VIA_STRING(VIA_DETAIL_CACHE_LOOKUP) != ' ');

  if (s->www_auth_content == CACHE_AUTH_FRESH) {
    s->hdr_info.server_request.method_set(HTTP_METHOD_HEAD, HTTP_LEN_HEAD);
    // The document is fresh in cache and we just want to see if the
    // the client has the right credentials
    // this cache action is just to get us into the hcoofsr function
    s->cache_info.action = CACHE_DO_UPDATE;
    dump_header(dbg_ctl_http_hdrs, &s->hdr_info.server_request, s->state_machine_id(), "Proxy's Request (Conditionalized)");
    return;
  }

  if (s->cache_info.write_lock_state == CACHE_WL_INIT) {
    // We do a cache lookup for DELETE, PUT and POST requests as well.
    // We must, however, delete the cached copy after forwarding the
    // request to the server. is_cache_response_returnable will ensure
    // that we forward the request. We now specify what the cache
    // action should be when the response is received.
    if (does_method_require_cache_copy_deletion(s->txn_conf, s->method)) {
      s->cache_info.action = CACHE_PREPARE_TO_DELETE;
      TxnDbg(dbg_ctl_http_seq, "cache action: DELETE");
    } else {
      s->cache_info.action = CACHE_PREPARE_TO_UPDATE;
      TxnDbg(dbg_ctl_http_seq, "cache action: UPDATE");
    }
  } else {
    // We've looped back around due to missing the write lock
    //  for the cache.  At this point we want to forget about the cache
    ink_assert(s->cache_info.write_lock_state == CACHE_WL_READ_RETRY);
    s->cache_info.action = CACHE_DO_NO_ACTION;
    return;
  }

  // if the document is cached, just send a conditional request to the server

  // So the request does not have preconditions. It can, however
  // be a simple GET request with a Pragma:no-cache. As on 8/28/98
  // we have fixed the whole Reload/Shift-Reload cached copy
  // corruption problem. This means that we can issue a conditional
  // request to the server only if the incoming request has a conditional
  // or the incoming request does NOT have a no-cache header.
  // In other words, if the incoming request is not conditional
  // but has a no-cache header we can not issue an IMS. check for
  // that case here.
  bool no_cache_in_request = false;

  if (s->hdr_info.client_request.is_pragma_no_cache_set() || s->hdr_info.client_request.is_cache_control_set(HTTP_VALUE_NO_CACHE)) {
    TxnDbg(dbg_ctl_http_trans, "no-cache header directive in request, folks");
    no_cache_in_request = true;
  }

  if ((!(s->hdr_info.client_request.presence(MIME_PRESENCE_IF_MODIFIED_SINCE))) &&
      (!(s->hdr_info.client_request.presence(MIME_PRESENCE_IF_NONE_MATCH))) && (no_cache_in_request == true) &&