/// <summary>
/// Extract context from the underlying text map carrier
/// </summary>
/// <param name="carrier"></param>
/// <returns></returns>
public SpanContext Extract(ITextMap carrier)
{
SpanContext context = null;
Dictionary <string, string> baggage = null;
string debugId = null;
bool contextParsed = false;
foreach (var item in carrier.GetEntries())
{
if (item.Key.Equals(contextKey))
{
contextParsed = SpanContext.TryParse(Decode(item.Value), out context);
}
else if (item.Key.Equals(Constants.DEBUG_ID_HEADER_KEY))
{
debugId = Decode(item.Value);
}
else if (item.Key.StartsWith(baggagePrefix))
{
if (baggage == null)
{
baggage = new Dictionary <string, string>();
}
baggage.Add(item.Key.MinusPrefix(baggagePrefix), Decode(item.Value));
}
}
if (!contextParsed)
{
if (!string.IsNullOrWhiteSpace(debugId))
{
return(SpanContext.Debug(debugId));
}
return(null);
}
if (baggage == null)
{
return(context);
}
return(context.SetBaggage(baggage));
}