Myujth

I was wondering is there any difference when using the @HysterixCommand annotation on a method that returns a DeferredResult over a method that returns an object straight away? Here is a sample of my code

@HystrixCommand(fallbackMethod = "getAlertsFallbackMethod")
public DeferredResult<List<AlertsBodyVO>> getAlerts(String userId) 
 LOGGER.info("Entered getAlerts - userId:", userId);
 final DeferredResult<List<AlertsBodyVO>> alertsDeferredResult = new DeferredResult<>();

 try 
 String requestURI = alertsEndpoint + userId.toUpperCase();
 LOGGER.info("requestURI:", requestURI);

 HttpHeaders headers = buildHttpHeader(userName, password);
 LOGGER.info("headers:", headers);
 HttpEntity<String> request = new HttpEntity<>(headers);
 LOGGER.info("request:", request);
 ResponseEntity<AlertsResponseVO> responseEntity = syncRestTemplate.exchange(requestURI, HttpMethod.GET, request, AlertsResponseVO.class);
 LOGGER.info("responseEntity:" + responseEntity);

 List<AlertsBodyVO> alertsBodyList = Arrays.asList(responseEntity.getBody().getAlertsBody());
 alertsDeferredResult.setResult(alertsBodyList);

 catch (final RestClientException rce) 
 LOGGER.error("ServiceImpl::getAlerts: failed for user__, --Cause::", userId, rce);
 ErrorResponseVO alertsResponse = new ErrorResponseVO();
 alertsResponse.setErrorMessage("ServiceImpl::getAlerts: failed for user__" + userId );
 alertsDeferredResult.setErrorResult(alertsResponse);
 
 LOGGER.info("Exiting:", alertsDeferredResult);
 return alertsDeferredResult;


public DeferredResult<List<AlertsBodyVO>> getAlertsFallbackMethod(String userId) 
 final DeferredResult<List<AlertsBodyVO>> alertsDeferredResult = new DeferredResult<>();
 LOGGER.info("CircuitBreaker:Fallback method for getAlerts returning empty object::userId: ",userId);
 return alertsDeferredResult;

Right after this line

 ResponseEntity<AlertsResponseVO> responseEntity = syncRestTemplate.exchange(requestURI, HttpMethod.GET, request, AlertsResponseVO.class)

The fallback method is called after 1 second.
I can see in the logs that the restTemplate completes successfully.

For Hysterix - I am using the default settings and this has worked fine for me in other methods that return objects.

If anyone can offer any insights into this behaviour it would be much appreciated.