Method handle_response_from_parent

src/proxy/http/HttpTransact.cc:3561–3699

////////////////////////////////////////////////////////////////////////// Name : handle_response_from_parent Description: response came from a parent proxy Details : The configuration file can be used to specify more than one parent proxy. If a connection to one fails, another can be looked up. This function handles responses from parent proxies. If the response is bad the next parent

//
///////////////////////////////////////////////////////////////////////////////
void
HttpTransact::handle_response_from_parent(State *s)
{
  auto next_lookup = ResolveInfo::UNDEFINED_LOOKUP;
  TxnDbg(dbg_ctl_http_trans, "(hrfp)");
  HTTP_RELEASE_ASSERT(s->current.server == &s->parent_info);

  // if this parent was retried from a markdown, then
  // notify that the retry has completed.
  if (s->parent_result.retry) {
    markParentUp(s);
  }

  simple_or_unavailable_server_retry(s);

  s->parent_info.state = s->current.state;
  switch (s->current.state) {
  case CONNECTION_ALIVE:
    TxnDbg(dbg_ctl_http_trans, "[hrfp] connection alive");
    s->current.server->connect_result = 0;
    SET_VIA_STRING(VIA_DETAIL_PP_CONNECT, VIA_DETAIL_PP_SUCCESS);
    if (s->parent_result.retry) {
      markParentUp(s);
    }
    // the next hop strategy is configured not
    // to cache a response from a next hop peer.
    if (s->response_action.handled) {
      if (s->response_action.action.no_cache) {
        TxnDbg(dbg_ctl_http_trans, "plugin set response_action.no_cache, do not cache.");
        s->cache_info.action = CACHE_DO_NO_ACTION;
      }
    } else {
      if (s->parent_result.do_not_cache_response) {
        TxnDbg(dbg_ctl_http_trans, "response is from a next hop peer, do not cache.");
        s->cache_info.action = CACHE_DO_NO_ACTION;
      }
    }
    handle_forward_server_connection_open(s);
    break;
  case PARENT_RETRY:
    if (s->current.retry_type == PARENT_RETRY_SIMPLE) {
      s->current.simple_retry_attempts++;
    } else {
      markParentDown(s);
      s->current.unavailable_server_retry_attempts++;
    }
    next_lookup           = find_server_and_update_current_info(s);
    s->current.retry_type = PARENT_RETRY_NONE;
    break;
  default:
    TxnDbg(dbg_ctl_http_trans, "[hrfp] connection not alive");
    SET_VIA_STRING(VIA_DETAIL_PP_CONNECT, VIA_DETAIL_PP_FAILURE);

    ink_assert(s->hdr_info.server_request.valid());

    s->current.server->connect_result = ENOTCONN;
    // only mark the parent down in hostdb if the configuration allows it and the parent,
    // is not congested, see proxy.config.http.parent_proxy.mark_down_hostdb in records.yaml.