internal StreamingInputStage(DataSource <R> source, Placement placement, InternalComputation internalComputation, string inputName)
{
this.inputName = inputName;
this.stage = Foundry.NewStage(new TimeContext <Epoch>(internalComputation.ContextManager.RootContext), (i, v) => new StreamingInputVertex <R>(i, v), this.inputName);
this.output = stage.NewOutput(vertex => vertex.output);
this.stage.Materialize();
this.localVertices = placement.Where(x => x.ProcessId == internalComputation.Controller.Configuration.ProcessID)
.Select(x => this.stage.GetVertex(x.VertexId) as StreamingInputVertex <R>)
.ToArray();
source.RegisterInputs(this.localVertices);
this.completedCalled = false;
this.hasActivatedProgressTracker = false;
// results in pointstamp comparisons which assert w/o this.
this.InternalComputation.Reachability.UpdateReachabilityPartialOrder(internalComputation);
this.InternalComputation.Reachability.DoNotImpersonate(stage.StageId);
var initialVersion = new Runtime.Progress.Pointstamp(stage.StageId, new int[] { 0 });
internalComputation.ProgressTracker.BroadcastProgressUpdate(initialVersion, placement.Count);
}