protected bool AddCacheEntryIfAbsent(string cacheKey, out HystrixCachedTask <RequestResponseType> entry)
{
var newEntry = new HystrixCachedTask <RequestResponseType>();
if (Properties.RequestCacheEnabled && cacheKey != null)
{
entry = _requestCache.PutIfAbsent(cacheKey, newEntry);
if (entry != null)
{
return(true);
}
}
entry = newEntry;
return(false);
}
public Task <RequestResponseType> ToTask()
{
RequestCollapser <BatchReturnType, RequestResponseType, RequestArgumentType> requestCollapser = collapserFactory.GetRequestCollapser(this);
CollapsedRequest <RequestResponseType, RequestArgumentType> request = null;
HystrixCachedTask <RequestResponseType> entry = null;
if (AddCacheEntryIfAbsent(CacheKey, out entry))
{
metrics.MarkResponseFromCache();
var origTask = entry.CachedTask;
request = entry.CachedTask.AsyncState as CollapsedRequest <RequestResponseType, RequestArgumentType>;
request.AddLinkedToken(_token);
var continued = origTask.ContinueWith <RequestResponseType>(
(parent) =>
{
CollapsedRequest <RequestResponseType, RequestArgumentType> req =
parent.AsyncState as CollapsedRequest <RequestResponseType, RequestArgumentType>;
if (req != null)
{
if (req.Exception != null)
{
throw req.Exception;
}
return(req.Response);
}
else
{
throw new InvalidOperationException("Missing AsyncState from parent task");
}
},
_token,
TaskContinuationOptions.ExecuteSynchronously,
TaskScheduler.Current);
return(continued);
}
try
{
request = requestCollapser.SubmitRequest(RequestArgument, _token);
entry.CachedTask = request.CompletionSource.Task;
return(entry.CachedTask);
}
catch (Exception ex)
{
return(Task.FromException <RequestResponseType>(ex));
}
}