public async Task <bool> SendTracesAsync(Span[][] traces)
{
if (traces == null || traces.Length == 0)
{
// Nothing to send, no ping for Zipkin.
return(true);
}
// retry up to 5 times with exponential back-off
var retryLimit = 5;
var retryCount = 1;
var sleepDuration = 100; // in milliseconds
while (true)
{
// TODO: Initially same code for Fx and Core.
var request = WebRequest.CreateHttp(_tracesEndpoint);
request.Method = "POST";
request.ContentType = "application/json";
using (var requestStream = await request.GetRequestStreamAsync().ConfigureAwait(false))
{
var serializer = new ZipkinSerializer();
serializer.Serialize(requestStream, traces, _settings);
}
Exception requestException = null;
HttpStatusCode requestStatusCode = 0;
try
{
using var httpWebResponse = (HttpWebResponse) await request.GetResponseAsync().ConfigureAwait(false);
// Zipkin specifies only "Accepted" as valid response, the code is more tolerant here.
// Following a criteria equivalent to HttpResponseMessage.EnsureSuccessStatusCode as
// done by the OpenTelemetry .NET SDK for their Zipkin exporter:
// See https://github.com/open-telemetry/opentelemetry-dotnet/blob/8cda9ef394a1b075fd156d73dace48e48f5b3c9b/src/OpenTelemetry.Exporter.Zipkin/ZipkinExporter.cs#L86
if (httpWebResponse.StatusCode >= HttpStatusCode.OK && httpWebResponse.StatusCode < HttpStatusCode.MultipleChoices)
{
return(true);
}
requestStatusCode = httpWebResponse.StatusCode;
Log.Debug("HTTP error sending traces to {0}: {1}", _tracesEndpoint, httpWebResponse.StatusCode);
}
catch (Exception ex)
{
requestException = ex;
Log.Debug("Exception sending traces to {0}: {1}", _tracesEndpoint, ex.Message);
}
if (retryCount >= retryLimit)
{
if (requestException != null)
{
Log.Error("No more retries, dropping spans. Last exception sending traces to {0}: {1}", _tracesEndpoint, requestException.Message);
}
else
{
Log.Error("No more retries, dropping spans. Last HTTP error sending traces to {0}: {1}", _tracesEndpoint, requestStatusCode);
}
return(false);
}
// retry
await Task.Delay(sleepDuration).ConfigureAwait(false);
retryCount++;
sleepDuration *= 2;
}
}