Async wrapper

NLog.Targets.OpenTelemetryProtocol.Test/Program.cs

@@ -1,4 +1,7 @@
-using System;
+using NLog.Targets.Wrappers;
+using System;
+using System.Diagnostics;
+using System.Linq;
 using System.Threading;
 
 namespace NLog.Targets.OpenTelemetryProtocol.Test
@@ -13,6 +16,7 @@ public static void Main()
 
             using var currentActivity = new System.Diagnostics.Activity("Hello World").Start();
 
+            logger.Fatal("message: {messageField}", message);
             logger.Fatal("message: {messageField}", message);
 
             Thread.Sleep(10000);

NLog.Targets.OpenTelemetryProtocol.Test/nlog.config

@@ -29,7 +29,6 @@
 	</targets>
 
 	<rules>
-
 		<logger name="*" writeTo="otlp" />
 	</rules>
 </nlog>

NLog.Targets.OpenTelemetryProtocol/ActivityExtensions.cs

@@ -0,0 +1,52 @@
+using System.Diagnostics;
+
+namespace NLog.Targets.OpenTelemetryProtocol
+{
+    /// <summary>
+    /// Formats elements of <see cref="Activity.Current"/> for inclusion in log events. Non-W3C-format activities are
+    /// ignored (Seq does not support the older Microsoft-proprietary hierarchical activity id format).
+    /// </summary>
+    internal static class ActivityExtensions
+    {
+        private static readonly System.Diagnostics.ActivitySpanId EmptySpanId = default(System.Diagnostics.ActivitySpanId);
+        private static readonly System.Diagnostics.ActivityTraceId EmptyTraceId = default(System.Diagnostics.ActivityTraceId);
+
+        public static string GetSpanId(this Activity activity)
+        {
+            return activity.IdFormat == ActivityIdFormat.W3C ?
+                SpanIdToHexString(activity.SpanId) :
+                string.Empty;
+        }
+
+        public static string GetTraceId(this Activity activity)
+        {
+            return activity.IdFormat == ActivityIdFormat.W3C ?
+                TraceIdToHexString(activity.TraceId) :
+                string.Empty;
+        }
+
+        private static string SpanIdToHexString(ActivitySpanId spanId)
+        {
+            if (EmptySpanId.Equals(spanId))
+                return string.Empty;
+
+            var spanHexString = spanId.ToHexString();
+            if (ReferenceEquals(spanHexString, EmptySpanId.ToHexString()))
+                return string.Empty;
+
+            return spanHexString;
+        }
+
+        private static string TraceIdToHexString(ActivityTraceId traceId)
+        {
+            if (EmptyTraceId.Equals(traceId))
+                return string.Empty;
+
+            var traceHexString = traceId.ToHexString();
+            if (ReferenceEquals(traceHexString, EmptyTraceId.ToHexString()))
+                return string.Empty;
+
+            return traceHexString;
+        }
+    }
+}

NLog.Targets.OpenTelemetryProtocol/OtlpTarget.cs

@@ -3,6 +3,7 @@
 using System.Collections.Generic;
 using System.Diagnostics.Tracing;
 using System.Globalization;
+using System.Linq;
 using System.Threading.Tasks;
 using Microsoft.Extensions.DependencyInjection;
 using Microsoft.Extensions.Options;
@@ -11,6 +12,7 @@
 using NLog.Layouts;
 using NLog.Targets.OpenTelemetryProtocol;
 using NLog.Targets.OpenTelemetryProtocol.Exceptions;
+using NLog.Targets.Wrappers;
 using OpenTelemetry;
 using OpenTelemetry.Exporter;
 using OpenTelemetry.Logs;
@@ -29,6 +31,7 @@ public class OtlpTarget : TargetWithContext
 
         private readonly ConcurrentDictionary<string, OpenTelemetry.Logs.Logger> _loggers = new(StringComparer.Ordinal);
         private readonly object _sync = new object();
+        private readonly object _sync2 = new object();
 
         private const string OriginalFormatName = "{OriginalFormat}";
 
@@ -67,6 +70,30 @@ public class OtlpTarget : TargetWithContext
 
         public bool DisableEventListener { get; set; }
 
+        public Layout TraceId { get; set; } = Layout.FromMethod(evt => System.Diagnostics.Activity.Current?.GetTraceId());
+
+        public Layout SpanId { get; set; } = Layout.FromMethod(evt => System.Diagnostics.Activity.Current?.GetSpanId());
+
+        private bool _checked = false;
+        private bool _isWrapped;
+
+        public bool IsWrapped
+        {
+            get
+            {
+                lock (_sync2)
+                {
+                    if (!_checked)
+                    {
+                        _checked = true;
+                        _isWrapped = LogManager.Configuration.AllTargets.Where(t => t is AsyncTargetWrapper).ToArray().Cast<AsyncTargetWrapper>().Any(x => x.WrappedTarget == this);
+                    }
+
+                    return _isWrapped;
+                }
+            }
+        }
+
         public OtlpTarget()
         {
             Layout = "${message}";
@@ -246,6 +273,16 @@ protected override void Write(LogEventInfo logEvent)
                 Timestamp = logEvent.TimeStamp,
             };
 
+            if (IsWrapped)
+            {
+                var spanId = RenderLogEvent(SpanId, logEvent);
+                if (!string.IsNullOrEmpty(spanId))
+                    data.SpanId = System.Diagnostics.ActivitySpanId.CreateFromString(spanId.AsSpan());
+                var traceId = RenderLogEvent(TraceId, logEvent);
+                if (!string.IsNullOrEmpty(traceId))
+                    data.TraceId = System.Diagnostics.ActivityTraceId.CreateFromString(traceId.AsSpan());
+            }
+
             if (IncludeFormattedMessage && (logEvent.Parameters?.Length > 0 || logEvent.HasProperties))
             {
                 var formattedMessage = RenderLogEvent(Layout, logEvent);

UnitTests/OpenTelemetry.Exporter.OpenTelemetryProtocol.Tests.csproj

@@ -60,6 +60,9 @@
   </ItemGroup>
 
   <ItemGroup>
+    <None Update="nlog2.config">
+      <CopyToOutputDirectory>Always</CopyToOutputDirectory>
+    </None>
     <None Update="nlog.config">
       <CopyToOutputDirectory>Always</CopyToOutputDirectory>
     </None>

UnitTests/TargetTests.cs

@@ -503,13 +503,39 @@ public void ActivityContextIsPopulated()
         using var currentActivity = new System.Diagnostics.Activity("Hello World").Start();
 
         logger.Info(message);
+        Assert.False(target.IsWrapped);
 
         OtlpLogs.LogRecord? otlpLogRecord = ToOtlpLogs(DefaultSdkLimitOptions, new ExperimentalOptions(), target.LogRecords[0]);
 
         Assert.Equal(currentActivity.TraceId.ToString(), ByteStringToHexString(otlpLogRecord.TraceId));
         Assert.Equal(currentActivity.SpanId.ToString(), ByteStringToHexString(otlpLogRecord.SpanId));
     }
 
+    [Fact]
+    public void ActivityContextIsPopulatedIfAsync()
+    {
+        LogManager.LoadConfiguration("nlog2.config");
+        var logger = LogManager.GetCurrentClassLogger();
+
+        OtlpTarget target = (OtlpTarget)LogManager.Configuration.AllTargets.First(x => x is OtlpTarget);
+        LogManager.ReconfigExistingLoggers();
+
+        var message = "message";
+
+        using var currentActivity = new System.Diagnostics.Activity("Hello World").Start();
+
+        logger.Info(message);
+
+        Thread.Sleep(10000);
+
+        Assert.True(target.IsWrapped);
+        Assert.Single(target.LogRecords);
+        OtlpLogs.LogRecord? otlpLogRecord = ToOtlpLogs(DefaultSdkLimitOptions, new ExperimentalOptions(), target.LogRecords[0]);
+
+        Assert.Equal(currentActivity.TraceId.ToString(), ByteStringToHexString(otlpLogRecord.TraceId));
+        Assert.Equal(currentActivity.SpanId.ToString(), ByteStringToHexString(otlpLogRecord.SpanId));
+    }
+
     private string ByteStringToHexString(Google.Protobuf.ByteString str)
     {
         return BitConverter.ToString(str.ToByteArray()).Replace("-", "").ToLower();

UnitTests/nlog2.config

@@ -0,0 +1,27 @@
+<?xml version="1.0" encoding="utf-8" ?>
+<nlog xmlns="http://www.nlog-project.org/schemas/NLog.xsd"
+		xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+		throwConfigExceptions="true"
+		internalLogLevel="Debug"
+		internalLogToConsole="true">
+
+	<extensions>
+		<add assembly="NLog.Targets.OpenTelemetryProtocol"/>
+	</extensions>
+
+	<targets async="true">
+		<target xsi:type="OtlpTarget"
+			name="otlp"
+			usehttp="true"
+			servicename="TestService"
+			scheduledDelayMilliseconds="1000"
+			useDefaultResources="false"
+			includeFormattedMessage="false">
+		</target>
+	</targets>
+
+	<rules>
+
+    <logger name="*" writeTo="otlp" />
+	</rules>
+</nlog>