public static List <Span> Apply(List <Span> spans)
{
var root = spans.FirstOrDefault(s => !s.parentId.HasValue);
if (root == null)
{
return(spans);
}
else
{
var tree = SpanNode.Create(root, spans);
Adjust(tree, null);
return(tree.ToSpans());
}
}
/**
* Recursively adjust the timestamps on the span tree. Root span is the reference point, all
* children's timestamps gets adjusted based on that span's timestamps.
*/
private static void Adjust(SpanNode node, ClockSkew skewFromParent)
{
// adjust skew for the endpoint brought over from the parent span
if (skewFromParent != null)
{
node.span = AdjustTimestamps(node.span, skewFromParent);
}
// Is there any skew in the current span?
var skew = GetClockSkew(node.span);
if (skew != null)
{
// the current span's skew may be a different endpoint than skewFromParent, adjust again.
node.span = AdjustTimestamps(node.span, skew);
// propagate skew to any children
foreach (SpanNode child in node.children)
{
Adjust(child, skew);
}
}
}
public static SpanNode Create(Span span, IEnumerable <Span> spans)
{
SpanNode rootNode = new SpanNode(span);
// Initialize nodes representing the trace tree
var idToNode = new Dictionary <long, SpanNode>();
foreach (var s in spans)
{
if (s.parentId.HasValue && s != span)
{
idToNode.Add(s.id, new SpanNode(s));
}
}
// Collect the parent-child relationships between all spans.
var idToParent = new Dictionary <long, long>();
foreach (var kvp in idToNode)
{
idToParent.Add(kvp.Key, kvp.Value.span.parentId.Value);
}
// Materialize the tree using parent - child relationships
foreach (var kvp in idToParent)
{
var node = idToNode[kvp.Key];
SpanNode parent;
if (idToNode.TryGetValue(kvp.Value, out parent))
{
parent.AddChild(node);
}
else
{
rootNode.AddChild(node);
}
}
return(rootNode);
}
private void AddChild(SpanNode node)
{
children.Add(node);
}