public Activity StartActivity(Activity activity, object?args)
{
activity.Start();
Write(activity.OperationName + ".Start", args);
return(activity);
}
private void RaiseRequestEvent(HttpWebRequest request)
{
if (request.Headers.Get(RequestIdHeaderName) != null)
{
// this request was instrumented by previous RaiseRequestEvent
return;
}
if (this.IsEnabled(ActivityName, request))
{
var activity = new Activity(ActivityName);
// Only send start event to users who subscribed for it, but start activity anyway
if (this.IsEnabled(RequestStartName))
{
this.StartActivity(activity, new { Request = request });
}
else
{
activity.Start();
}
if (activity.IdFormat == ActivityIdFormat.W3C)
{
// do not inject header if it was injected already
// perhaps tracing systems wants to override it
if (request.Headers.Get(TraceParentHeaderName) == null)
{
request.Headers.Add(TraceParentHeaderName, activity.Id);
var traceState = activity.TraceStateString;
if (traceState != null)
{
request.Headers.Add(TraceStateHeaderName, traceState);
}
}
}
else
{
// do not inject header if it was injected already
// perhaps tracing systems wants to override it
if (request.Headers.Get(RequestIdHeaderName) == null)
{
request.Headers.Add(RequestIdHeaderName, activity.Id);
}
}
if (request.Headers.Get(CorrelationContextHeaderName) == null)
{
// we expect baggage to be empty or contain a few items
using (IEnumerator <KeyValuePair <string, string> > e = activity.Baggage.GetEnumerator())
{
if (e.MoveNext())
{
StringBuilder baggage = new StringBuilder();
do
{
KeyValuePair <string, string> item = e.Current;
baggage.Append(WebUtility.UrlEncode(item.Key)).Append('=').Append(WebUtility.UrlEncode(item.Value)).Append(',');
}while (e.MoveNext());
baggage.Remove(baggage.Length - 1, 1);
request.Headers.Add(CorrelationContextHeaderName, baggage.ToString());
}
}
}
// There is no guarantee that Activity.Current will flow to the Response, so let's stop it here
activity.Stop();
}
}