/// <summary>
/// OnMethodBegin callback
/// </summary>
/// <typeparam name="TTarget">Type of the target</typeparam>
/// <param name="instance">Instance value, aka `this` of the instrumented method.</param>
/// <param name="callback">The AsyncCallback delegate</param>
/// <param name="state">An object containing state information for this asynchronous request</param>
/// <returns>Calltarget state value</returns>
internal static CallTargetState OnMethodBegin <TTarget>(TTarget instance, AsyncCallback callback, object state)
{
if (instance is HttpWebRequest request && WebRequestCommon.IsTracingEnabled(request))
{
var tracer = Tracer.Instance;
// We may have already set headers
var propagator = SpanContextPropagator.Instance;
var requestContext = propagator.Extract(request.Headers, (headers, headerName) => headers.GetValues(headerName) ?? Enumerable.Empty <string>());
if (requestContext is null || requestContext.TraceId == TraceId.Zero)
{
var span = ScopeFactory.CreateInactiveOutboundHttpSpan(tracer, request.Method, request.RequestUri, WebRequestCommon.IntegrationId, out _, traceId: null, spanId: null, startTime: null, addToTraceContext: false);
if (span?.Context != null)
{
// Add distributed tracing headers to the HTTP request.
// We don't want to set an active scope now, because it's possible that EndGetResponse will never be called.
// Instead, we generate a spancontext and inject it in the headers. EndGetResponse will fetch them and create an active scope with the right id.
propagator.Inject(span.Context, request.Headers, (headers, key, value) => headers.Set(key, value));
}
}
}
return(CallTargetState.GetDefault());
}
/// <summary>
/// OnMethodBegin callback
/// </summary>
/// <typeparam name="TTarget">Type of the target</typeparam>
/// <param name="instance">Instance value, aka `this` of the instrumented method.</param>
/// <returns>Calltarget state value</returns>
internal static CallTargetState OnMethodBegin <TTarget>(TTarget instance)
{
if (instance is HttpWebRequest request && WebRequestCommon.IsTracingEnabled(request))
{
var tracer = Tracer.Instance;
if (tracer.Settings.IsIntegrationEnabled(WebRequestCommon.IntegrationId))
{
var span = ScopeFactory.CreateInactiveOutboundHttpSpan(tracer, request.Method, request.RequestUri, WebRequestCommon.IntegrationId, out _, traceId: null, spanId: null, startTime: null, addToTraceContext: false);
if (span?.Context != null)
{
// Add distributed tracing headers to the HTTP request.
// The expected sequence of calls is GetRequestStream -> GetResponse. Headers can't be modified after calling GetRequestStream.
// At the same time, we don't want to set an active scope now, because it's possible that GetResponse will never be called.
// Instead, we generate a spancontext and inject it in the headers. GetResponse will fetch them and create an active scope with the right id.
SpanContextPropagator.Instance.Inject(span.Context, request.Headers.Wrap());
}
}
}
return(CallTargetState.GetDefault());
}
