internal static RequestTelemetry CreateRequestTelemetryPrivate(
this HttpContext platformContext)
{
if (platformContext == null)
{
throw new ArgumentNullException(nameof(platformContext));
}
var result = new RequestTelemetry();
var currentActivity = Activity.Current;
var requestContext = result.Context.Operation;
if (currentActivity == null)
{
// if there was no BeginRequest, ASP.NET HttpModule did not have a chance to set current activity (and will never do it).
currentActivity = new Activity(ActivityHelpers.RequestActivityItemName);
if (ActivityHelpers.IsW3CTracingEnabled)
{
ActivityHelpers.ExtractW3CContext(platformContext.Request, currentActivity);
ActivityHelpers.ExtractTracestate(platformContext.Request, currentActivity, result);
// length enforced in SetW3CContext
currentActivity.SetParentId(currentActivity.GetTraceId());
W3COperationCorrelationTelemetryInitializer.UpdateTelemetry(result, currentActivity, true);
SetLegacyContextIds(platformContext.Request, result);
}
else if (currentActivity.Extract(platformContext.Request.Headers))
{
requestContext.ParentId = currentActivity.ParentId;
}
else if (ActivityHelpers.TryParseCustomHeaders(platformContext.Request, out var rootId, out var parentId))
{
currentActivity.SetParentId(rootId);
if (!string.IsNullOrEmpty(parentId))
{
currentActivity.SetParentId(rootId);
if (!string.IsNullOrEmpty(parentId))
{
requestContext.ParentId = parentId;
}
}
}
else
{
// As a first step in supporting W3C protocol in ApplicationInsights,
// we want to generate Activity Ids in the W3C compatible format.
// While .NET changes to Activity are pending, we want to ensure trace starts with W3C compatible Id
// as early as possible, so that everyone has a chance to upgrade and have compatibility with W3C systems once they arrive.
// So if there is no current Activity (i.e. there were no Request-Id header in the incoming request), we'll override ParentId on
// the current Activity by the properly formatted one. This workaround should go away
// with W3C support on .NET https://github.com/dotnet/corefx/issues/30331
currentActivity.SetParentId(StringUtilities.GenerateTraceId());
// end of workaround
}
currentActivity.Start();
}