JaegerProgator for OpenTelemetry (extract only)

JaegerPropagator.cs

using OpenTelemetry;
using OpenTelemetry.Context.Propagation;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;

namespace ProperNamespace
{
    internal class JaegerPropagator : TextMapPropagator
    {
        public override ISet<string> Fields => new HashSet<string> { PROPAGATION_HEADER };

        private const string PROPAGATION_HEADER = "uber-trace-id";
        private const string PROPAGATION_HEADER_DELIMITER = ":";

        private const int MAX_TRACE_ID_LENGTH = 2 * 16;
        private const int MAX_SPAN_ID_LENGTH = 2 * 8;
        private const int MAX_FLAGS_LENGTH = 2;

        public override PropagationContext Extract<T>(PropagationContext context, T carrier, Func<T, string, IEnumerable<string>> getter)
        {
            if (context.ActivityContext.IsValid())
            {
                // If a valid context has already been extracted, perform a noop.
                return context;
            }

            if (carrier == null)
            {
                return context;
            }

            if (getter == null)
            {
                return context;
            }

            try
            {
                var traceparentCollection = getter(carrier, PROPAGATION_HEADER);
                // There must be a single traceparent
                if (traceparentCollection == null || traceparentCollection.Count() != 1)
                {
                    return context;
                }

                var traceparent = traceparentCollection.First();
                var traceparentParsed = TryExtractTraceparent(traceparent, out var traceId, out var spanId, out var traceoptions);

                if (!traceparentParsed)
                {
                    return context;
                }

                return new PropagationContext(
                    new ActivityContext(traceId, spanId, traceoptions, null, isRemote: true),
                    context.Baggage);
            }
            catch (Exception ex)
            {
            }

            return context;
        }

        internal static bool TryExtractTraceparent(string traceparent, out ActivityTraceId traceId, out ActivitySpanId spanId, out ActivityTraceFlags traceOptions)
        {
            traceId = default;
            spanId = default;
            traceOptions = default;

            var parts = traceparent.Split(PROPAGATION_HEADER_DELIMITER);
            if (parts.Length != 4) return false;

            if (!IsTraceIdValid(parts[0])) return false;
            traceId = ActivityTraceId.CreateFromString(parts[0].AsSpan());


            if (!IsSpanIdValid(parts[1])) return false;
            spanId = ActivitySpanId.CreateFromString(parts[1].AsSpan());


            // parts[2] is ignored
            if (!IsFlagsValid(parts[3]) || !int.TryParse(parts[3], out int flags)) return false;
            traceOptions = flags == 1 ? ActivityTraceFlags.Recorded : ActivityTraceFlags.None;

            return true;
        }

        private static bool IsTraceIdValid(string value)
        {
            return !(string.IsNullOrWhiteSpace(value) || value.Length > MAX_TRACE_ID_LENGTH);
        }

        private static bool IsSpanIdValid(string value)
        {
            return !(string.IsNullOrWhiteSpace(value) || value.Length > MAX_SPAN_ID_LENGTH);
        }

        private static bool IsFlagsValid(string value)
        {
            return !(string.IsNullOrWhiteSpace(value) || value.Length > MAX_FLAGS_LENGTH);
        }

        public override void Inject<T>(PropagationContext context, T carrier, Action<T, string, string> setter)
        {
        }
    }
}