public virtual async Task <T> GetNextItemAsync()
{
if (_getDataFunc == null)
{
throw new ArgumentNullException($"{nameof(GetDataFrom)} hasn't been called");
}
EnsureFetchTaskIsRunning();
if (InternalBuffer == null)
{
throw new DataflowException("You must call StartInput first. The buffer has not been initialized");
}
var fetchCalled = TryFetchData();
if (!HasItemsInQueue)
{
return(null);
}
//if (fetchCalled) _dataLoadSemaphore.WaitOne();
var item = await _propagationBlock.ReceiveAsync();
if (ItemAvailableforProcessing != null)
{
await ItemAvailableforProcessing.Invoke(this, new DataSourceEventArgs <object> {
Items = new[] { item }
});
}
_signal.Set();
return(item);
}
