public async Task SaveSurveyResponseAsync([FromBody] ClientModels.SurveyAnswer surveyAnswer)
{
if (surveyAnswer == null)
{
throw new ArgumentNullException(nameof(surveyAnswer));
}
if (ModelState.IsValid)
{
try
{
var queue = await _stateManager.GetOrAddAsync <IReliableConcurrentQueue <ClientModels.SurveyAnswer> >("surveyQueue");
if (surveyAnswer.Id == null)
{
surveyAnswer.Id = Guid.NewGuid().ToString();
}
using (var tx = _stateManager.CreateTransaction())
{
await queue.EnqueueAsync(tx, surveyAnswer);
await tx.CommitAsync();
}
}
catch (Exception ex)
{
ServiceEventSource.Current.ServiceRequestFailed(ex.ToString());
throw;
}
}
}
public async Task MergeSurveyAnswerToAnalysisAsync([FromBody] ClientModels.SurveyAnswer surveyAnswer)
{
try
{
var surveyAnswersSummaryCache = Connection.GetDatabase();
var success = false;
do
{
var result = await surveyAnswersSummaryCache.StringGetAsync(surveyAnswer.SlugName);
var isNew = result.IsNullOrEmpty;
var transaction = surveyAnswersSummaryCache.CreateTransaction();
SurveyAnswersSummary surveyAnswersSummary = null;
if (isNew)
{
transaction.AddCondition(Condition.KeyNotExists(surveyAnswer.SlugName));
surveyAnswersSummary = new SurveyAnswersSummary(surveyAnswer.SlugName);
}
else
{
surveyAnswersSummary = JsonConvert.DeserializeObject <SurveyAnswersSummary>(result);
transaction.AddCondition(Condition.StringEqual(surveyAnswer.SlugName, result));
}
ServiceEventSource.Current.Message("Slug name:{0}|Total answers:{1}", surveyAnswersSummary.SlugName,
surveyAnswersSummary.TotalAnswers);
// Add and merge the new answer to new or existing summary
surveyAnswersSummary.AddNewAnswer(surveyAnswer.ToSurveyAnswer());
transaction.StringSetAsync(surveyAnswer.SlugName,
JsonConvert.SerializeObject(surveyAnswersSummary));
//This is a simple implementation of optimistic concurrency.
//If transaction fails, another user must have edited the same survey.
//If so, try to process this survey answer again.
//Another approach is to store each survey answer option as a separate hash in Redis and simply increment
//the hash value. This technique will not cause collisions with other threads but will require a redesign of
//how survey answer summaries are stored in redis. This approach is left to the reader to implement.
success = await transaction.ExecuteAsync();
} while (!success);
}
catch (Exception ex)
{
ServiceEventSource.Current.ServiceRequestFailed(ex.ToString());
throw;
}
}
public static ApiModels.SurveyAnswer ToSurveyAnswer(this ClientModels.SurveyAnswer surveyAnswer)
{
if (surveyAnswer == null)
{
throw new ArgumentNullException(nameof(surveyAnswer));
}
return(new ApiModels.SurveyAnswer()
{
CreatedOn = surveyAnswer.CreatedOn,
QuestionAnswers = surveyAnswer.QuestionAnswers.Select(qa => qa.ToQuestionAnswer()).ToList(),
SlugName = surveyAnswer.SlugName,
Title = surveyAnswer.Title
});
}
