public static IList <KeyExtractorNode <T> > Aggregate(IEnumerable <KeyExtractorNode <T> > source)
{
var aggregator = new NodeAggregator <T>();
var result = source
.GroupBy(ken => ken.Path, (path, @group) =>
(Node)@group.First().ReplaceNestedNodes(
new ReadOnlyCollection <BaseFieldNode>(
@group.SelectMany(ken => ken.NestedNodes).ToList())))
.Select(aggregator.Visit)
.Cast <KeyExtractorNode <T> >()
.ToList();
return(result);
}
public IEnumerator <TItem> GetEnumerator()
{
var currentTaskCount = sessionHandler.PrefetchTaskExecutionCount;
var aggregatedNodes = NodeAggregator <TItem> .Aggregate(nodes);
var resultQueue = new Queue <TItem>();
var container = new StrongReferenceContainer(null);
foreach (var item in source)
{
resultQueue.Enqueue(item);
if (item != null)
{
foreach (var extractorNode in aggregatedNodes)
{
container.JoinIfPossible(RegisterPrefetch(extractorNode.ExtractKeys(item), extractorNode));
}
}
if (currentTaskCount == sessionHandler.PrefetchTaskExecutionCount)
{
continue;
}
while (container.JoinIfPossible(sessionHandler.ExecutePrefetchTasks()))
{
container.JoinIfPossible(ProcessFetchedElements());
}
while (resultQueue.TryDequeue(out var resultItem))
{
yield return(resultItem);
}
currentTaskCount = sessionHandler.PrefetchTaskExecutionCount;
}
while (container.JoinIfPossible(sessionHandler.ExecutePrefetchTasks()))
{
container.JoinIfPossible(ProcessFetchedElements());
}
while (resultQueue.TryDequeue(out var resultItem))
{
yield return(resultItem);
}
}
public async IAsyncEnumerator <TItem> GetAsyncEnumerator(CancellationToken token = default)
{
var currentTaskCount = sessionHandler.PrefetchTaskExecutionCount;
var aggregatedNodes = NodeAggregator <TItem> .Aggregate(nodes);
var resultQueue = new Queue <TItem>();
strongReferenceContainer = new StrongReferenceContainer(null);
var enumerationIdentifier = Guid.NewGuid();
async IAsyncEnumerable <TItem> ProcessItem(TItem item1)
{
resultQueue.Enqueue(item1);
if (item1 != null)
{
foreach (var extractorNode in aggregatedNodes)
{
var fetchedItems =
await RegisterPrefetchAsync(extractorNode.ExtractKeys(item1), extractorNode, enumerationIdentifier, token).ConfigureAwait(false);
_ = strongReferenceContainer.JoinIfPossible(fetchedItems);
}
}
if (currentTaskCount == sessionHandler.PrefetchTaskExecutionCount)
{
yield break;
}
while (strongReferenceContainer.JoinIfPossible(
await sessionHandler.ExecutePrefetchTasksAsync(token).ConfigureAwait(false)))
{
_ = strongReferenceContainer.JoinIfPossible(await ProcessFetchedElementsAsync(enumerationIdentifier, token).ConfigureAwait(false));
}
while (resultQueue.TryDequeue(out var resultItem))
{
yield return(resultItem);
}
currentTaskCount = sessionHandler.PrefetchTaskExecutionCount;
}
if (source is IAsyncEnumerable <TItem> asyncItemSource)
{
await foreach (var item in asyncItemSource.WithCancellation(token).ConfigureAwait(false))
{
await foreach (var p in ProcessItem(item).WithCancellation(token).ConfigureAwait(false))
{
yield return(p);
}
}
}
else
{
var items = source is IQueryable <TItem> queryableSource
? await queryableSource.ExecuteAsync(token).ConfigureAwait(false)
: source;
foreach (var item in items)
{
await foreach (var p in ProcessItem(item).WithCancellation(token).ConfigureAwait(false))
{
yield return(p);
}
}
}
while (strongReferenceContainer.JoinIfPossible(
await sessionHandler.ExecutePrefetchTasksAsync(token).ConfigureAwait(false)))
{
_ = strongReferenceContainer.JoinIfPossible(await ProcessFetchedElementsAsync(enumerationIdentifier, token).ConfigureAwait(false));
}
while (resultQueue.TryDequeue(out var resultItem))
{
yield return(resultItem);
}
}