public override IAsyncCursor <TResult> Aggregate <TResult>(IClientSessionHandle session, PipelineDefinition <NoPipelineInput, TResult> pipeline, AggregateOptions options, CancellationToken cancellationToken = default(CancellationToken))
{
Ensure.IsNotNull(session, nameof(session));
var renderedPipeline = Ensure.IsNotNull(pipeline, nameof(pipeline)).Render(NoPipelineInputSerializer.Instance, _settings.SerializerRegistry, _linqProvider);
options = options ?? new AggregateOptions();
var lastStage = renderedPipeline.Documents.LastOrDefault();
var lastStageName = lastStage?.GetElement(0).Name;
if (lastStage != null && (lastStageName == "$out" || lastStageName == "$merge"))
{
var aggregateOperation = CreateAggregateToCollectionOperation(renderedPipeline, options);
ExecuteWriteOperation(session, aggregateOperation, cancellationToken);
// we want to delay execution of the find because the user may
// not want to iterate the results at all...
var findOperation = CreateAggregateToCollectionFindOperation(lastStage, renderedPipeline.OutputSerializer, options);
var forkedSession = session.Fork();
var deferredCursor = new DeferredAsyncCursor <TResult>(
() => forkedSession.Dispose(),
ct => ExecuteReadOperation(forkedSession, findOperation, ReadPreference.Primary, ct),
ct => ExecuteReadOperationAsync(forkedSession, findOperation, ReadPreference.Primary, ct));
return(deferredCursor);
}
else
{
var aggregateOperation = CreateAggregateOperation(renderedPipeline, options);
return(ExecuteReadOperation(session, aggregateOperation, cancellationToken));
}
}
public static ICoreSessionHandle ToCoreSession(this IClientSessionHandle clientSession)
{
var coreSession = new ClientSessionWrappingCoreSession(clientSession.Fork());
return(new CoreSessionHandle(coreSession));
}
public IClientSessionHandle Fork()
{
return(_sessionHandle.Fork());
}
