internal AsyncLookup(
IAsyncEnumerable <TSource> source,
Func <TSource, Task <TKey> > keySelector,
Func <TSource, Task <TElement> > elementSelector,
IEqualityComparer <TKey> keyComparer)
{
_keySelector = keySelector;
_elementSelector = elementSelector;
_iterator = source.GetAsyncEnumerator();
_factory = new TaskFactory(new LimitedConcurrencyLevelTaskScheduler(1));
_dictionary = new ConcurrentDictionary <TKey, AsyncGrouping <TKey, TElement> >(keyComparer);
_completed = new TaskCompletionSource <bool>();
_inProgress = new PartialAsyncCollection <AsyncGrouping <TKey, TElement> >(MoveNextUntied);
}
private async Task CompleteIteration()
{
//Should only be called by MoveNextInternal
Debug.Assert(_inProgress != null);
foreach (var grouping in _dictionary.Values)
{
await grouping.MarkComplete();
}
await _inProgress.CompleteAdding();
_completed.TrySetResult(true);
_inProgress = null;
//Clear out other items we'll no longer need
_keySelector = null;
_elementSelector = null;
_iterator = null;
}