Function cont_handle_response

plugins/background_fetch/background_fetch.cc:514–559

///////////////////////////////////////////////////////////////////////// Main "plugin", which is a global READ_RESPONSE_HDR hook. Before initiating a background fetch, this checks: 1. Check if a background fetch is allowed for this request and 2. Is the response from origin a 206 (Partial)? We defer the check on cacheability to the SEND_RESPONSE_HDR hook, since there could be other plugins that

// there could be other plugins that modifies the response after us.
//
static int
cont_handle_response(TSCont contp, TSEvent event, void *edata)
{
  // ToDo: If we want to support per-remap configurations, we have to pass along the data here
  TSHttpTxn      txnp   = static_cast<TSHttpTxn>(edata);
  BgFetchConfig *config = static_cast<BgFetchConfig *>(TSContDataGet(contp));

  if (nullptr == config) {
    // something seriously wrong..
    TSError("[%s] Can't get configurations", PLUGIN_NAME);
  } else {
    switch (event) {
    case TS_EVENT_HTTP_READ_RESPONSE_HDR:
      if (config->bgFetchAllowed(txnp)) {
        TSMBuffer response;
        TSMLoc    resp_hdr;

        if (TS_SUCCESS == TSHttpTxnServerRespGet(txnp, &response, &resp_hdr)) {
          // ToDo: Check the MIME type first, to see if it's a type we care about.
          // ToDo: Such MIME types should probably be per remap rule.

          // Only deal with 206 and possibly 304 responses from Origin
          TSHttpStatus status = TSHttpHdrStatusGet(response, resp_hdr);
          Dbg(Bg_dbg_ctl, "Testing: response status code: %d?", status);
          if (TS_HTTP_STATUS_PARTIAL_CONTENT == status || (config->allow304() && TS_HTTP_STATUS_NOT_MODIFIED == status)) {
            // Everything looks good so far, add a TXN hook for SEND_RESPONSE_HDR
            TSCont localcontp = TSContCreate(cont_check_cacheable, nullptr);

            TSHttpTxnHookAdd(txnp, TS_HTTP_SEND_RESPONSE_HDR_HOOK, localcontp);
          }
          // Release the response MLoc
          TSHandleMLocRelease(response, TS_NULL_MLOC, resp_hdr);
        }
      }
      break;
    default:
      TSError("[%s] Unknown event for this plugin", PLUGIN_NAME);
      Dbg(Bg_dbg_ctl, "unknown event for this plugin");
      break;
    }
  }

  // Reenable and continue with the state machine.
  TSHttpTxnReenable(txnp, TS_EVENT_HTTP_CONTINUE);
  return 0;
}

///////////////////////////////////////////////////////////////////////////
// Setup global hooks